Whatever you do don't buy a cheap rack because you'll be surprised at the problems you'll have, bikes banging into one another, rack stuff breaking with no parts to buy to fix it, etc. If you can't afford more than $90 then look for a really nice used one.
I have a hitch model myself called the Bonelocker, but it's kind of expensive plus the cost of the hitch, but it does incorporate a built in locking system that locks the bikes to the hitch, and it's so sturdy that the weight of the bikes doesn't make it move at all. You can install a hitch on any car and for a beginner with some mechanical skills, but not a lot is needed, it may take an hour. The hitch brand isn't important just get one from Walmart, it's a light duty hitch which is WAY overrated to haul bike on! But even though you mount a hitch on a car do not think that you can haul a camping trailer or some other heavy trailer to it because most cars today are not designed to tow anything heavy.
You can read about that bike rack here: http://www.thebonelocker.com/ After trying a couple different ones previously I really like this one way over the others I've had, and it's built to last unlike the others.