Hey Frapstery,
Thank you so much for using my tileset in your game! I'll take a look at it as soon as I can.
Yes, I am available to do custom works for these tilesets. In terms of price if its small quantities, its an item by item basis which relies on the sprite size. So if you are interested in getting a few parts done, you can email me at dragoonwys@gmail.com so we can discuss in length what ya need! ^o^
In terms of internal tiles, I will be expanding these gradually, like this expansion if you haven't seen it~ So you can look forward to those if you are not in a rush.
Cheers,
Wys