Try a local Coin and Stamp dealer. Coin and Stamp folk use 10X loupes also.
Coin folk scrutinize coins for scuffs, bag marks, scars, die marks, and defacing. Paper money and stamp people look at creases, corners, the ink, the list goes on and on. We have slider style, larger sized 5X's that we carry in our pockets to whip out for a quick check. We have the 10X's that fold back into the circle protectors and a lighted 10X as well. We also have a 20X and a 40X "Hallmark" loupes.
The specialized ones were bought on-line. The rest came from Coin and Stamp Shows and local shops. A Coin and Stamp dealer should have a reasonably priced 10X in stock.
I did some research on moderately priced ones before I purchased and ended up buying a Belomo loupe on ebay for $19.00. They are very high quality triplets for the price and have a larger lens than most standard loupes.
Hubby bought the 20X and 40X for his coin and currency collecting. He sometimes uses them to check mint marks, creases, and such. They weren't bought for looking at gems, but we have used them for that!