Need some assistance with a couple of items I'm looking to sell

I've got a couple of items I might be looking to sell to fund another project, but I'm not quite sure what the value is.

1. Factory X Gladiator Maximus Helmet with base (base is a little scratched up) no box or paperwork. Custom paint job
2. Blue Realm Studios (Devin White) Halo 3 MC helmet with lights

Thanks in advance for the help!