I'm just browsing for a cheap one atm for myself. I got rid of my last one due to size restraints (I need at least 8" on a X or Y axis) but this next one I'll be looking for a cheaper one if possible. If one of you have a 3D printer you want to trade for a tank you let me know I've got all kinds!
As for the batteries stick with NIMH for now unless you are comfortable with learning a few new things. Lipo is safer and cheaper than ever before but it still requires a bit of knowledge about safety before you start. Once you follow the simple rules you are fine Lots of guys here run lipo and I myself almost exclusively run lithium.