Update: For some reason I couldn't reply to your response kstrauser so here is my reply: That works if and when their is trust. First you have trust the buyer isn't going to abuse the system and wreck the IP [reputation] and you have to trust the buyer isn't giving you stolen info. Obviously things one can work through but again, it involves trust. Also the provider has to have warmed up IPs to give out. Which, having warmed up IPs would actually be a great valued add upsell for those that need them!
Update 2: Thank you FfejL and symfoniq for explaining it better.