As Ill Logic said, I believe that anti price fixing laws should be repealed. This is because I believe the free market will do a better job of regulating itself than the government can.
To understand how the market regulates itself, you have to understand the most fundamental part of the market; price. Price is the value of a good (or service) agreed upon between a producer and a consumer. When each of these parties are negotiating the price of a good, they take into account the supply of and the demand for the good. With a greater supply the price is lower, and with a greater demand the price is higher. The reason for this is simple. If the supply is much higher than the demand, then either the cost of producing the good is very low or the good is not valued highly by the consumers. Either way, a consumer would not be willing to pay a high price for the good. The same is true for demand. When it is high then there isn't enough of the good to satisfy the need of all those who demand it. The price rises to ensure that those who's need is greatest get what they need, and those who can do without don't stock up and capitalize on the shortage.
These economic laws are a part of human nature and can't be broken easily, if at all. The most prominent attempt is when suppliers or governments artificially limit supply through prohibition, rationing, or set a price ceiling or floor. Every time this is done, a black market springs up to conduct business without government restriction. Bootlegging, drugrunning, scalping, smuggling, and off-the-books labor are the results of these government interventions in the market. They are alive and well today, despite all the government's efforts to eliminate them.
That fact is the crux of my argument that restrictions that prohibit price fixing should be eliminated. Right now, businesses are colluding to increase prices above what demand necessitates. This is inevitable, just as illegal drug sales and under-the-table workers earning less than the law states are inevitable. Therefore with a law prohibiting price fixing, we are not considering a world where there is no price fixing, we are just considering one where there is less price fixing. How much less? That depends on how intrusive the investigations into alleged collusion are. To prove one's innocence, one must prove a negative, that they didn't negotiate with their competitors. To prove that someone is guilty, the investigator must find some very subtle evidence that the people who's job it is to set the price at which they will offer a good have set it unnecessarily high in cooperation with their competitors, and not due to market conditions, bad business decisions, independent greed, or plain old stupidity. These are very difficult things to prove without heading too far down the path of fascism, which is why few people are found guilty. Or it would be why, if not for the self regulation of the free market.
The major reason that relatively few cases of price fixing exist is because of competition. For a price fixing arrangement to work, it would require the cooperation of everyone who produces that good. However, if any producer were to backstab their co-conspirators and undercut the fixed price, they would get much more business than all their competitors. The competitors would then have to either abandon their higher price, offer a better value to their customers to justify their price, or sacrifice their business to the undercutter. What's more, in an ideal world they would have to control all of the means to produce the good or else a new competitor would spring up and sell it at the regular price. This factor is somewhat lessened by more government intervention, like licensing, intellectual property, and minimum wage laws, but it is there and would be even stronger if the government would back off in those areas.
This is all the protection from price fixing that is necessary. Since wrongdoing would be hard to prove as I said before, and lowering the artificial barrier to entry for new competitors would be very easy and unable to be abused, that is the better method for preventing price fixing.