Ok, I'm first going to say this. Otium Silva is one of my favorite hecking maps, and I love you for making it!
Now on to the commissions. Heck yes. However, I'm terrible at pricing, but I'll wing it.
Small Map: $5/500 points
Medium Map: $7/700 points
Large Map: $10/1000 points
You can tweak those prices depending on how detailed the maps are. Less detailed maps may cost a tad less. Those are just base prices.
And honestly, I'd take both money and points for it. On DA of course you can put up commissions widgets and convert the points (even though it takes longer to get the actual money) that way more people can commission you.
If you open map commissions, I'll definitely be your first customer!
I think that all looks swell! But on the sky, I think if it's just normal custom stuff there shouldn't be extra charge. However for something special (different particles and what not) you can charge a bit more. ^^