Where to acquire tech pins?

So I have an idea in the works, but need to get a hold of some pins for a tech binding. For early testing purposes I figure I can get away with grinding the ends of bolts down and threading them into the part they'd ideally be welded to, but it seems most tech binding replacement parts are for larger and more expensive pieces. Just a student with limited resources, and the thing I'm trying to make is first and foremost for myself and friends. I'll re-evaluate my options if this skips the "oh that's a dumb idea, move on" phase.