Hehe, yeah. Well, the client wants what the client wants. I often suggest changes to geography when I take on a commission, usually for impossible rivers etc. but sometimes a map is already "set in stone" and there's no room for change. It's a fantasy land though, right? Anything can happen.
Amazing! Stunning! AWESOME! I'm not only a dauber, I'm also a gamesmaster, and I love RPGs and fantasy worlds. I would like to ask you a commission in the near future, if you don't mind. To have my world drew by you would be so awesome!
I guess it depends on what style of map you want to go for and which tutorials (if any) you follow. Many methods of creating maps can be done perfectly well with a mouse.
For myself though I would be completely lost without my tablet. My maps are all hand drawn and the fact that I am left handed makes drawing with a mouse a complete waste of time as I still hold it the traditional way (in my right hand). My "Vaniya" map was the first one I did and was done without a tablet but I think it really shows - I used some pretty ropey brushes I made for the mountains.
If I were you I would go give a few tutorials a try and see if it's something you'd like to learn to do better before splashing out on a tablet.
Umm, not sure in euros but prices range from about £20 up to really expensive. I think mine cost about £60 or so. I can vouch for the Wacom Bamboo as a good entry-level tablet. I wouldn't trust the really cheap ones.