2 golden gecho pelts(the boots)
But boots are metal too!!1

Just make requirements like it's now but +golden gecko pelts, so everyone will need also hunt poor lizards, not only 1 time run to HQ mine.
Or not upgraded metal armor will require alot regular metal parts as pre-wipe metal armor, and upgrade will require HQ metal. You'll need to make 3 none-HQ-mine runs to craft metal armor, and then 1 HQ-mine run to upgrade it.
Or merge this both, so you'll need 3 none-HQ-mines runs, then kill some golden geckos, then 1 HQ-mine run.