Fastener kits are pricey for good stuff, as you've learned. There isn't any cheap way to get one unless you buy out a shop that is going out of business. I buy good stuff at OreillyAuto, Fastenal, NAPA, Lowes or HomeDepot. I usually buy a couple extra fasteners when I buy what I need so I'll have extras to put in my bolt box.
I have one of those three drawer plastic things FULL of bolts in one drawer and nuts in another lol. I really need a metal box for them.
1969 Chevy RCLB C10 350/TH400 SOLD
2007 Chevy RCSB 4.8 4x4 LS SOLD
2008 Chevy RCSB 5.3 4x4 LT SOLD
2010 Chevy CCSB 6.2 4x4 LT SOLD
2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
2013 FORD CCSB F350 6.7 Powerstroke 4x4