I assume you mean the Trade Fed droid armies? The basic battle droid was controlled remotely, so they could be sold off as-is for labor droids. (I think they were a derivation of a labor droid to start with?) More specialized droids like the B2 & Droideka models would need more significant work on their processing cores to render them suitable for a civvie market. I can see stripped bodies with no weapons or processors being offered for sale. Heck, that'd be a great way to stimulate the economy - create a need for specialist droid reconditioning services.
I'm thinking a lot of the higher-end droids got recycled for their raw materials. Altho... a crime-lord with a handful of droidekas could be an interesting problem...