It's cool. We're not trying to be unwelcoming or unhelpful at all...and whatever deal you make would, of course, be between you and the cartographer.

If I were looking at taking the job for free I'd probably say that you could use the result on your site and to promote/educate about your books but would want to negotiate a fee at a later time for it to appear in a commercial product (and I'd be willing to take a per/item royalty in lieu of an up-front fee if that worked better for you and we could work out the accounting process). That's just me, though, and others may have different ideas.
M