I see people having hard times "giving" their guild away for free so I don't think theres much interest for this.
also I've never done such a thing but I'd think you make him officer promote him to guildleader. accept payment (there can be 2 guildleaders right?). leave. (ithink.......)
Someone offered me a free guild months ago. He had a GH and a bunch of npcs(don't remember how many) but it was around 100k worth of npcs. I managed to sell for 30k after a lot of convincing. It's a hard sell thats for sure