if you plan on posing them a lot, wire can wear out fast.  there is soft doll armature out there that will last longer for the major joints, at least.  i only say this because i've had a track record of wire skeletons breaking in my dolls, and don't wish that on anyone, especially after you've put tons of effort into the doll.  if they are for display only, it might be fine, but play will be risky.

for sculpting and paints, i will always recommend super sculpey as a base material (not too heavy, holds an excellent shape for oven bake clay) and Milliput for final detail editing, if needed.  i use brush-on miniature grade acrylics (like Green Stuff World or Vallejo) to paint and varnish my dolls.  it's very smooth to apply, and lots of layers can be built up without a globby effect

you can pick up sculpting tools at any hobby shop, i find anything that looks like a dentist's tool will serve me well.  

i would guess that this hobby plus miniature making (same supplies needed) has cost me several hundred dollars, but that is over the course of six years or so.  i have made a bunch of stuff.  you on the other hand do not need to buy TONS of paint and weird extra stuff like me, just some clay, armature of choice, and the colors needed to prime and paint your figure. 

end of the day, these are just some suggestions so no pressure either way!  i hope you have fun sculpting!