I'm about to buy a second hand  cheap bass guitar. he said he bought it at 2011. Is that okay to buy this ? because i dont understand these things, Perhaps it would be a problem, if its old one . its 100Turkish liras ( about 20$ or 25$)
Age itself isn't an issue, and 2011 isn't very old. My second bass is a 1989 Carvin LB75 five-string in perfect condition.

If you don't know what you're doing buying a bass, find someone who knows more and can help you out. You don't want to end up with a piece if kindling at any price.