Get the starter box, as you will need 2 sides to have a fight. It's a good value. Just abit of warning though. The models are need assembly. While it's a pain in the neck to put them together, it allows for tremendous customization of the figures, no 2 figs need to be the same. I think that outweighs the pain of assembly.
Also heads up, if your new to this forum, you may not know, that starting in August, Mongoose will be releasing pre-painted box sets of the figures. So if you don't like to model or paint, then you might want to wait till then.
Cheers, Xin