Hyper 7 TQ kit $210
JR XS3 radio $150
Then your still light an engine but should be able to pick up a hyper 8 port for under $100 on ebay.
Thats about a minimum fairly competative setup
You can go for RTR but the radio isn't upto much as said above.
The good thing about the hypers is that spares are aplenty and there is a good range of hopups available so the buggy can grow with you.
I would steer clear of the ultra comp too. If your serious about 1/8th you'll be selling it soon for an upgrade