The Xray XB9 seems to be one of the better cars out right now. Xray is renowned for it's durability and long lasting parts. You really don't need much for spares and eliminates the need to have an LHS that stocks everything.
You won't find an Xray part on the shelf anywhere near this area, but you see plenty of the cars on the track and winning.
It's a solid car that handles great and will last a long time.
Engine wise, stick with major name brands and you'll be ok. My personal preference is Novarossi and OS engines. I've tried some of the cheaper brands and I went back to paying a little more for a reason.
You can get a great Novarossi engine that makes great power and run time for close to $200. Look at Fusion X as well, they are made by Novarossi.
OS XZB is a great one
Bullitt is made by OS
Mugen Ninja is also an OS and excellent performing motor
A lot of the cheaper motors are very enticing when you see them running. They are fast, but they just don't last as long and can be much more difficult to tune. If you want to get into nitro and save yourself some serious frustration, I highly suggest a OS motor. They are widely regarded as the easiest engine to tune out there.