Also, for the caps you get it isn't worth it. Other than slavers, EEEEEVVVERRRYONE absolutely HATES slavers. They are more or less seen as one step above childkillers or the way a PC gets looked at if they pull heat, start striding around a large city and shooting the poor, slitting open prostitutes with rippers and turning the gentry's heads into shotgun skeets.
Once you get the slaver's mark, its kind of like having '666 heil hitler 666' bordered with swastikas tattooed onto your forehead and walking into a synagogue. Only everywhere. Only those who are in between 'bastard' and 'total bastard' will want anything to do with you. As long as they are just below 'enclave' in terms of their bastarditis then such people would trade with and talk to you; but those groups, don't forget (metzger etc) aren't the sort you can get very useful equipment from, and if you haven't got it already, there are a lot of people that won't deal with you for supplies.
Your best supplier of weapons is probably going to end up being the enclave as a result, given how heavily armed they are. But that also means GETTING said weapons. Which, given they are trying to kill you, means the only way that their weapons are going to be exchanged for your caps, is they empty their magazines into you and then they take the caps from your cooling carcass as the crows pick the juicy bits from your eyesockets.