if you are planning on racing only advice that is good is look at what the people are running, and look what the shop carries as when something breaks you WILL need replacements, and it royally sucks to wait 3 days if you need it right away at a track

Basically you will have to pick a class, and power source before anyone can really recommend much

if looking at Short course trucks (they seem most popular) for 2wd The HPI Blitz from what I read is a pretty good starter, and as HPI is fairly common most hobby shops should have parts available. I've actually looked into getting one a few times when I had some spare cash laying around, but just couldn't find a good deal on one at the times.
4wd short course the nexx 10SC (but high chance parts will have to be ordered online, and its sold as a kit so it will cost $100+ to get running on top of kit cost). I have its predecessor which shares like 90% or parts, and can say the parts are pretty robust


as for how much to spend you will need to factor in the support equipment so if electric figure in at least $150-$180 for 2 sets as chargers are around $40-50 a pop batteries $20-30 a pop (this is ordering online if from a hobby shop the equivalent stuff will be 2-3X more )

so for example if you go with the blitz flux which is $350, and need 2 the total cost will be around $900 for the RC's and support equipment.

Now if you want $500 total for 2 that might not be possible...

btw this hobby is expensive at the start cause the support equipment really racks up the cost, but once you have that it gets relatively cheap over the long term next to most hobbies.