Where can I buy quality garage door rollers?

You can buy replacement garage door rollers any retail hardware store like a Lowes or Home Depot. These types of rollers that you can buy these retail hardware stores will be of around the 15,000 cycle grade. These are just fine for your average every day residential steel garage door. They run anywhere from $5-$10 per roller. If you want a roller that has more cycles then you will have to call a local garage door company to acquire a garage door roller that has more than 15,000 cycles. Garage door suppliers do not generally sell to the general public the only other place you will build to find these types of rollers is on the Internet sites including eBay and craigslist. This is the only place you will find that these types of rollers because they do not generally sell to the general public you have to have a contractors license or a business license saying that you are in the garage store business.

replacing the garage door rollers is about 75 to $250

Depending on what state you live in. Just communicate this with the garage door company that you regularly use and they should have a solution for you.  If you do not know anything about garage doors there is no reason for anyone to try to replace their rollers without any knowledge of what needs to be done especially because of the torsion spring danger involved which you will have to deal with if you are going to replace a set of garage door rollers. Warning if you have no knowledge of a torsion spring then messing with it can cause serious injury or death. This obstacle will arise when you have to change the bottom rollers on the left and right hand side of the door. These rollers are attached to the bottom bracket which is also attached to cables that run to the top of the torsion pole which the spring is under high tension in order to lift the garage door. A fair price range for replacing the garage door rollers is about 75 to $250. This price range will depend on what kind of garage door that you have and what kind of garage door roller it will require.