Not a ton unfortunately as 60H Charge Gatling exist from Scavenger during events. The Gatlings are about 20 if you can find a seller, and they have more ATA than the Vulcans.
So maybe 10+ for the Vulcs. That said I haven’t seen many 60H Gatling or 55H Vulcans traded recently so they could go for more.
60H is when the price jumps to 100+.