Hi, Ill tell you right now, finding a aero kit under $50 is not a picnic! Ive got a suggestion:
Have you ever heard of the Great Planes FireBat? It looks like a su 22 jet. I Purchased a kit early this year from tower hobbies for 54.99. The body is all foam though. But its held together great. Its electric and includes nothing. But the ultimate combo (which includes everything!) is only 199.99. You should checkout Model Airplane news magazine and see the tests they have preformed on the FireBat. I can honestly say that it is worth the money. Has great low speed responce and suprisingly fast fly-bys! Only bad thing is it has to be hand launched there is no freagin landing gear.

You cant go wrong with this one...