Reddit reviews 5 - 1 Inch Contoured Aluminum Side Release Buckles

That's the 1" Alu-max buckle - I've used some different ones but theirs has a great finish and holds up the best. here they are on amazon, but I can't remember where I bought mine

First, double check the warantee, some retailers like REI might be more customer friendly about claims than the maker, but it looks like it pretty much will leave you getting a $2 replacement part. Buy 3, if it broke once, it most likely will again.

Second option, Sea to Summet have no-sew for adjustable buckles if the whole body breaks.

Third option, find a shoe maker, ask them about bag options, or find some appropriate buckles and have them replaced that way. This will most likely void what is left of the warantee, but it seems that that covers defects in manufacture, which if not discovered at this point are probably nonexistent in their view. A worthless warantee is not worth worrying about, you own the bag, make it so you can use it.