Buying used D7000
I just purchased used Nikon D7000 on ebay for $500. Seller had 100% rating (90 reviwers) and claimed that camera is in excellent condition with 25k clicks. Now after purchasing this I realized that I couldve gotten factory refurbished one for $100 more from Cameta which will also come with 1 year warranty. Did I make a hufe mistake by making my initial purchase one ebay? How will I know everything is working perfectly once I receive it? Also how can I check if my D7000 have well known focusing problem?
I am panicking at the moment because this is a big purchase for me and I'm not sure if I made the right choice. I will greatly appreciate any kind of help. Thank you and take care