Bridle leather is definitely the one to go for. It strikes me that a definite element of the price of a good belt is the attachment of the buckle. A lot nowadays use rivets or Chicago screws (solid brass being best), but others use the more traditional stitching method. That in turn varies the cost, depending on the number of rows, stitches per inch and so on. Things like the handmade Hawkmoth Leather Co. belts from Sussex are things of beauty, but the price.......!
I suppose that, in theory, metal fastenings should be more durable than stitching, but I have a stitched belt I bought in 1969 from a Norwich saddler for £1.11s.6d, which has never needed resewing.