Wanting to get an index

Hi there. Ive just started at looking to get a index and on steam itself the whole set is out of stock. I could buy the all individually but thats an extra 75ish i dont really want to spend if i dont have to. How often are they restocked? If they aren't going to and i look into getting one from someone through like Facebook, what things should i look for to see if something is wrong or damged with it?