don't worry about used instruments; check them carefully, that's all. 90% of my instruments have been used. Truth be told, most of the finest instruments are used, think Stradivarius for a few million each. Anyway, try to get 88 keys if Piano is what you want to study. A decent work around is a used controller with weighted keys, like a Fatar SL-990, and a used piano module, probably under $500 if you shop carefully. As for learning, forget the gimmicks like lighted keys; if Ray Charles didn't need them, neither do you. I can't play my way out of a paper bag on the piano, but I have been an earnest student of the guitar since 1965, and can read, and understand basic harmony, so I understand playing music, and love to share my enthusiasm for playing. An honest half hour a day will show results like you wouldn't believe, and you'll shortly improve to the point where a half hour isn't nearly enough... just go get one, and wave your freak flag high; you can always resell it.
Steve