There are strapmakers who are more talented than other strapmakers, just like with your watch you will understand the quality of the experience when something is not right with the strap or when there is a wear and tear that needs to be taken care of. Some give an unconditional warranty on all straps they make for life and no questions asked what happened to the strap, they just replace the strap, some are a deaf ear when you are asking them the change the stitching with another color and instead make you a new offer for a strap at a full price again.
Second there are strapmakers who make the latest and greatest straps that are popular at the moment, you cannot blame the strap maker to charge a bit more for the "brand" you buy. You should also look further than just the piece of leather used, is it vegetable tanned leather or not, is the strap completely hand-sewn, does the maker create his/her own buckles, are there special leather types used, etc.
I once had two ammo straps, one 350$ made by a very famous strapmaker, the other one $100 by a new strapmaker and enjoyed both of them.
That doesn't mean a strap should always have to cost you more than 100$ to be a nice strap, but the same is with shoes, clothes and watches. I recently spotted a new Seike Pressage watch for 400$, super nice and would not mind to wear one besides my 10,000$ Panerai.
You have to make out for yourself what strap is singing to you, after that you can always ask for references, maybe not on this forum, maybe better to do that on FB, just to prevent shilling.
Dutchman, Panerista since 2014 and learning
PAM389 and PAM372 and a bunch of straps