Basically, you pay me money, I make you a map! There are 3 basic types of commissions I offer, but I'm flexible; PM me with details and what you're willing to pay if you would like to commission a map and we can work something out. The three types are:
A basic pixel map, not necessarily of the whole world (or our world). One of these will cost roughly $12, depending on how much you want out of it. See my WorldA and Pixel gallery for more examples.
Basic Vector: $20
A basic vector map of a country or region, featuring a few cities and rivers. Add-ons will cost extra, depending on how large the add-on you want is.
I recommend Inkscape! It's a great (and free) vector program that's pretty similar to Adobe Illustrator. Or, if you're going for something a bit more pixel-oriented, I'd go with GIMP, which is kinda-sorta the free version of Photoshop.