I don't mind paying for the item ahead of time to ensure the owner I'm going to do business with them.

But let's say hypothetically that I gained or loss a great deal of weight. Let's say I moved two sizes. I don't know what size I "need", I only know I want that model. I'm going to buy the item, but want the correct size. If a bike store does not want a high overhead and inventory to carry every size and every color (which is reasonable), then he should be willing to accommodate those customers that fall outside the middle of the road. That's the price of doing business.

On a side note as a response to an earlier post about tires. BearSquirrel, I'm not a "demanding" customer, all I was asking for was option #2. There are dozens of tire manufacturers out there and I would expect a shop owner to have more than one option available. So I believe his response to my "I don't care for these tires because of x, y, z," should have been "I'm sorry to hear that. Why don't we try a, b, or c as I have had very good reports of those brands. Then I would have said great, let's try b.

I guess I'm lucky I don't get gun shy with my customers if they don't like my first idea.