Hey, i have something extra to add if you don't mind
this guide is pretty decent for newly started guild seller and buyers.
You can buy a newly transfered guild to ur server with 0 members lvl 20, and still make alot of cash on that... now how can i do that? because guilds with no members in it can get sold very cheap, and recruting members isnt hard! ever had the guys spamming guild invites to you? well ofc you have, if you run honorbuddy you can use Guild recruter with a twist, were the bot auto invites, that is what i do,i get 100+ members in my guild ever day, and i have to kick inactives to get more room for active people follow this link: [PimpMyGuild] - The ultimate guild recruiter! (I DO NOT TAKE CREDIT FOR MAKING THIS PLUGIN).
Also watch out for guild names when ur purchasing them, bad names arent worth buying high, atleast not if u dont plan on using 20 euros on changing the name on it, or X realm transfer.
If you find out someone is selling a guild with a bad guild name, you can point it out to them and maybe get it so cheap it's a robbery, and try resell it for a bit higher.
Atm i got two lvl 25 guilds that im just stacking up with active members and getting ready for MOP, i aim for 4-5 lvl it fast up in MOP and resell when u hit max lvl cap there, and earn a TON of gold!
Ps excuse my bad English