Slightly different to the normal type of LARP gear shops, Armor Geek sells leather working patterns for various items like gauntlets, greaves, books and backpacks.
If you’re interested in leatherworking or simply suck at making patterns (like me!) then check this site out. The patterns are affordable and the produce items look easily modifiable, so you can make an item for a fraction of the price and to the exact look you’re after.