There's an Army Navy store clear across town that I like to frequent. They have a good selection, as if I stocked the store, and good prices. I buy what I can from them when I can. For odd holsters they have an amazing junk pile of old(er), outdated holsters. I bring a gun I want a holster for and with their permission I try the fit on various holsters. I'm not familiar with all the brands and sizes so I eyeball it and if it's close and a style I like I try it on.
If you're buying first quality you may end up paying more than an online purchase but what you get is a sure fit and you support your local gun shop.