there is no way to determine how old is list . Best way to check quality of list is to send sample emails to 100 -500 peoples and check what response you get .
According to my experience there is no place . because if someone have good email list either he/she would not sell it or sell it at very high cost like $2 per email .... however there are lot of claims buy one million emails in $100 such claims are often fake . Best way to get email list is Set up an E-mail only campaign with some small affiliate nertwork however one email will cost you appx. $1.5 (standard industry rate) with network set up fee and network fee..
Maybe this site can be helpful. http://www.mailing-lists-direct.com/ They sell mailing lists to webmasters.
We've bought lists from Electric Marketing before which have been good, they're UK based though, http://www.electricmarketing.co.uk/