Apparently the logo design belongs to the guild, so it would be a copyright violation for anyone to copy it without permission (so it's good that you asked first). You could inquire about purchasing a license to make a set number of items with the logo. That way the guild would get some income while still protecting the use of their logo, the members would be able to purchase items made with the logo, and you would also get some income. However before doing that you might want to make sure that the guild members are interested in purchasing the items. I think your customer base would probably not extend outside the guild, unless the logo is very generic.