What about price-fixing?
Price fixing would require every single company selling something to cooperate. And if they do, another person sick of them can start a new company and undercut them. Price fixing would also destroy any goodwill towards these companies and many customers wouldn't patronize them even if they lowered their prices again.
We have to distinguish between two types of creations. We'll discuss how the cost of coming up with both can be recouped without intellectual property and its awfulness.
If the resource is replaceable, like fossil fuels, the free market will invest appropriately in alternatives as and when needed. As for irreplaceable resources, it would be a very rare situation for there to only exist a few sources of it globally, controlled by a few entities, and for them to all stop competing and fix prices. This would be a global crisis requiring international action and co-operation for diplomacy, sanctions, and acquiring new sources/technologies. Clearly not a usual scenario that can be used to dismiss libertarianism.
A customer that can afford it may willingly overpay for a product due to brand affinity/prestige. Even otherwise, there are 8 billion people on the planet. Getting $10 profit from 100 million people means a billion dollars in profit. None of the 100 million people need to have been poor or exploited; small profits per person can result in a billionaire simply due to the large human population. This is not to say that all current billionaires obtained all their wealth through such innocent means – many have used violence or state assistance – just that it is possible.
The owners of roads are incentivized to set reasonable rules so that people want to use their roads.
What about abortion?
First let's discuss the argument against abortion. Most people would save the life of an infant over that of an animal, even if the animal is more intelligent. The only unbiased reason to do this is that given nutrients, the baby will develop into a more intelligent lifeform in the future. Thus wanting to save a "clump of cells" isn't as irrational as it may seem.
But our hypothetical above assumes that both the baby and the animal want to live. By not killing themselves, all conscious creatures have implicitly expressed their desire to continue living, and most people agree that that is to be respected, at least for humans. Which is why killing a person painlessly while they're unconscious is still considered wrong. But this desire does not apply to fetuses before the third trimester, which have never been conscious. This is the moral argument for abortion. There is also the obvious utilitarian argument for it.
Libertarian morality is as follows: According to the principle of homesteading, each man owns his
own person, and he therefore owns the things which he produces – those parts of nature hitherto unowned and which,
when mixed with his labor, are transformed into productive
entities. The only moral ways for these entities to change ownership are voluntary trade and gift-giving.
Those who are productive with their property become
responsible for more and more, since they can afford to buy up additional property with their earnings. The overall productivity therefore, will rise.
Figure 1. If only consent was respected in more than sex. Marx's response was that it's not really consensual since the worker is bound to unwanted labour as a means of survival. The libertarian morality of "you still can't force someone to pay you more than your labor is worth" isn't satisfactory to non-libertarians, so see the section on welfare for a discussion of the provision of basic necessities in libertarianism, as well as the one on minimum wage. Either way, there are currently thousands of economic restrictions that are nowhere near essential for survival.
Some sewage systems, power generation, forests, beaches, etc., may currently be government owned. They can also be redistributed similar to roads and the water supply. Any profits gained by these will be distributed proportional to the shares owned.
Meta
What about welfare?
The libertarian opposition to government-funded welfare is based on of course, ideals of voluntaryism, but also on the efficiency of private entities. Simply giving the poor money is not the best way to end poverty. With private charities, the ones that can actually cause change in a neighbourhood will get donations, and inefficient ones won't. This will likely involve putting conditions on the money given, eg., that the able-bodied and able-minded must participate in education/employment. There's also the task of making such initiatives as efficient as possible.
If a pseudo-libertarian government were to forcibly collect money for welfare, it would be best to decouple the voting for the NAP-enforcing and welfare-providing branches, but there would still be a big problem.
If contributing to welfare was compulsory and the welfare provider was voted upon democratically, the votes of wealthy charity givers that want to see change would be drowned out by the votes of the poor that would prefer to receive money with no strings attached, and the votes of the upper and middle classes that want their contributions reduced. And if the voting isn't democratic, the system will be overthrown by the people. But reducing compulsary welfare via the votes of the upper and middle class is currently possible if all of them could be convinced that it is misplaced kindness.
The main concern people have regarding abolishing welfare is whether enough money will be donated to cover all poor people. The rich who can afford to donate large amounts already do, be it out of kindness or to acquire goodwill, and people would certainly donate a lot more if they didn't already have to pay half their money in income, property, value-added, excise, and numerous other taxes, for the "betterment of society". Libertarians believe that this, combined with the fact that the best performing charities will be the ones donated to, mean that poverty will be alleviated with less money needing to be spent.
We can't definitively prove this yet, so why not first test things out by slowly reducing the scope of government welfare? It must not all be cut suddenly, since time will be needed for the culture surrounding welfare to shift as people pay less in taxes, and for private charities to strengthen and become effective.