RE: Newbie wants in
If you're looking to go racing, as much as ThunderbirdJunkie adores his XXX-SCT (2wd SCT is the biggest class at most tracks), the Kyosho Ultima SC-R is really the way to go.
Between radio, power system, batteries, etc, it'll be very easy to wind up with a grand or more to get started into the truck...but realistically, the SC-R is a better deal than the XXX-SCT, and as you said, you might as well go whole hog from the get-go.
SC-R
$400
No upgrades needed for the truck itself and all the materials are top notch.
XXX-SCT roller
$180
TLR tuning kit
$130
That's $310 right there
Then you add in some graphite parts (front bulkhead, shock towers, etc) and that's $60 right there, spare CVA's since the stockers wear quickly (ThunderbirdJunkie is running old XXX-T universals instead), 'bout $30, replace all the crappy stock captured rod ends with ball cups, about $25...the list goes on and on.
2wd 1/10 buggy is a cheaper class to get into, and cheaper to maintain. The TLR 22 and RC10B4.1FT are the best ways to go for a race car and the most supported by onsite hobby shops. The 22 is easier to drive and tougher, the B4.1FT is more "hairy" when it comes to handling, both are very fast and capable of propelling a good driver to a good finish anywhere. If you get a 22, put a Losi XXX diff gear with 12 balls in it during the initial build.
Beyond that, a decent radio is around $200-400 (ThunderbirdJunkie would recommend picking up a used Futaba 3PKS with the 2.4 FASST module and a receiver or two, shouldn't set you back more than a couple hundred), and ultimately, a Tekin RS Pro combo for motivation, although there are some really nice budget systems out there (DualSky's stuff from ckhobby.com is definitely worth checking out; Mike is a good guy, tell him ThunderbirdJunkie sent you)
Again, the Losi truck is awesome. But it develops slop more quickly than the SC-R, and is more expensive to get into "top tier" racing condition, and it's not quite as tough as the SC-R. Bear in mind that the Kyosho Ultima SC is not the same as the SC-R; they may as well be classified as completely different trucks despite using a number of the same or similar parts. Also, the Losi will likely be easier to get parts for should something go awfully wrong at a sensitive time (like during the last free-run of the day, 20 minutes before your main)
Another suggestion is head to the track and see what the local guys have for sale used. With buying a used car online, you never know what you're getting. ThunderbirdJunkie has scored some sweet deals over the years at the track (the B4.1 ThunderbirdJunkie currently has he paid $100 for as a roller with 3 race days on it, was in way better shape than his old B4 which he sold for $150[&:])
Mind you, these are all racing suggestions. ThunderbirdJunkie has separate play and race cars...he doesn't bomb around with his race cars out in the street, and he doesn't take his play cars to the track.
If you want to go 4wd SCT racing, well...then you're looking at a bigger pile of cash to do it right. ITBJHO that class isn't mature enough to make newbie-friendly suggestions.