They are easy to sell, a shop will buy 10 to 100, depending on the shop & if they can sell them onto other like shops.
Head shops, second hand shops, pawn shops. Sell them by hand or stalls for extra profit.
Normally a shop will buy for about 1/3 to 1/2 their retail, ask them what they would sell them for or work out your profit margins.

You need to take the primers out, drill (wear saftey glasses & earmuffs, never had one go bang, but theres always a first time) pick or hydrolic method, thats easyer & safer, uses water too.
Army ammo can't be reloaded without a rework because of the primer design.
So its easyish to come by, find a reloader & get both the shells & tracer tips at the same time.

Tracer tips are longer & reloaders buy expired tracer ammo & reload them with hunting or target practice projectiles.
You have to drill the tracer mix out & thru the metal wall, melt the lead out & redrill the tip out & polish.

By using the correct bullet shells you can use a small shell as the mouth peice, it slips onto the larger ones neck.
Dosn't look as good, but its a lot faster.

To polish, use a bench grinder with a polishing mop & some car polishing compound.
Put a 'easyout' in a hand drill & reverse the drill & put the projectile or shell on the easyout & start the drill up & polish the metal part against the polishing mop.
Thats 10 times faster & better looking than just the bench polishing mop.

The ear plug things only need a copper pipe cutter ($10 or less) & a hammer & swadge to form the chamfer & 2 'O' rings, easy job that one, good earner too, 2 at a time...