What made your interest focus on the DEX210? I'm not saying it's a bad car, in fact the design is good, but spares are not cheap and there have been parts batches with sub-standard material quality/durability...
If you decide to go DEX210, I'd get a second hand one - there's usually a good bunch of tuning parts on there that put it near or at the V2 spec for a fraction of the price. If you like the car you can then buy another one in better condition (or new) so you can use the other for spares (which takes care of the spares problem)
As for the DEX210 RTR, it's an o-k deal, but it uses a first version tub chassis (which is prone to breakage), has no parts for Mid-motor and the motor is, well... boringly slow
You're better off getting a HobbyKing X-car ESC (100A or 120A) and a 6.5-8.5T motor to start off.
As for other cars: Look at the B5M, BMAX2MR, VBC Firebolt and Schumacher KF as well.