I used to play tennis regularly in my teens... started out with those lakri kay rackets the ones common in the 80's... then used my dad's aluminium dunlop racket, (i cant be stuffed typing the correct spelling)... broke it after a while,,, and mind u, some of those aluminium rackets arent lighter than the graphite ones... but I do agree with the tennis elbow being painful.. cos i did suffer from it... You wont develop tennis elbow if ur playing like an insaan ka bacha,,, but if ur janglee like myself,, always in josh trying to be mark phillipousis with the serves and volley or from the baseline, then you better choose ur racket wisely.. having said all that, I,ve owned dunlop, wilson and prince.... I would say, dont go for something dirt cheap... around a 100 dollars should get you a decent quality racket from one of these well known brands like wilson, head, prince, dunlop etc.
having said all that, it was my dream to get a prince racket when I was young... so i,d go for prince... but anything around 100 bucks sound give u a decent quality racket... cos trust me,, the cheap ones arent good,, the rackets for hire they have at our uni are some cheap brand, and they suck big time!
also, your style of tennis also determines what you want, and oversized head? a smaller size and the normal medium sized head... also, the tension of ur strings,, depends on ur style of tennis... as a beginner, u can get anything decent and as ur style develops,, u can move to a racket of ur choice... its about the feel as well,, so instead of buying it online, why dont u go to a shop and try it out a little? the grip, the shape, the weight, u have to feel right about it too....