If there is a "Spec Slash" class at your club, then that would be an excellent way to get started for around $200, but don't be fooled into thinking that is all you will spend... plan to budget about another $300+ on hidden expenses to get a Slash that is truly race ready. The
PR buggy I referenced earlier will be less expensive to get started with and be competitive. A box stock Slash will be at a huge disadvantage without necessary upgrades.
I would not recommend any Traxxas product unless it's a "Spec" class, all of the Traxxas designs are severely dated with minimal tuning options and will be more labor intensive to maintain.
Key reasons why I wouldn't race a Slash:
1) No sealed diffs limits tuning window
2) No threaded shocks
3) Limited Spring selection
4) No Sway Bars
5) No Emulsion Shocks
6) Too many upgrades needed which make it cost prohibitive