I've got a collection.....
First off, FMS: You don't want to spend anything close to $50 on it. That would be a total waste of money. I got mine off of ebay for about $15 including a tx lead (JR to printer). I even consider that a waste now, I wouldn't advise getting it unless you've got an old PC that won't run a half decent sim.
Cockpit Master: Good if you can get it cheap. Then you've got to spend some $30 odd to get the lead. Cheapest is the 'proper' one on Hobby Lobby (I think).
Ripmax RC Simulator: Best of the bunch at this price range. For around $50 you get a half decent sim with a joystick interface. The interface comes with a windows driver so you can use your transmitter to control any joystick game. You can pay more for this just for the interface on its own, and you can also use it with Cockpit Master too.
Easyfly: Got mine on ebay for around $15 (must've been lucky). Good, but I wouldn't recommend paying more than around $25 for it. You just have the one island to fly around and the area around the main runway is very tight with no easy way to see where the runway actually is once you're up there... Good fun but no real good trainer aircraft and no upgrades to speak of.
G2: Finally splashed out the other day to find out what all the hype is about. It just that: hype. Don't get me wrong, it really is a good sim and maybe worth the $200 they want for it. But unless you've got the latest and greatest PC, the frame rates will get you and you'll be out hunting for a new graphics card (ask me how I know)....