Have a look at the risk you put yourself in when you settle for cheap ATV tires. Firstly cheap ATV tires would obviously be of inferior quality than a branded and reputed one.
Since the whole load and functioning of an ATV falls on the tires, it would be extremely dangerous to take the risk by putting inferior quality cheap ATV tires. Secondly, since you are just looking at the price and not the quality you would obviously have to buy the tire from a dealer who would not assure you about the guarantee or warranty of the tires. Cheap ATV tires can be the cause of major accidents on a difficult terrain.
However, if you are still convinced that you only want cheap ATV tires the best place to start looking is on the internet. You would get a number of dealers and can do a price comparison easily. Tire auctions are also an option you can look at. There maybe used tires or someone selling off a tire he doesn’t need and you may get a good bargain in such cases. There are many online tire shopping websites that offer good deals and discounts too. You have to make the choice between quality and price and then decide if cheap ATV tires are the best choice for you or not.