My suggestion is to get this set, a single Ifantry Squad and a Chimera. If you put the
HWTs into Platoons (as you should) you'll get guys spare to make a Platoon Command Squad, and can do a list like this:
CCS, Chimera
Platoon:
PCS
Infantry Squad
Infantry Squad
Veteran Squad, Chimera
Russ
It runs about 750-800ish points depending on setup, a good size to start off with, and gives you some very useful units. If you decide you want a mechanised/tank army then the Platoon can still be used as an objective sitter, if you want an Infantry army the Chimera Vet Squad and
CCS can be nice interference units in that.