You'll probably have to look in our 'For Sale' sub-forum, or on Ebay for a used one. They have been out of production for a while now. I faced the same problem a couple years ago, and I couldn't find a new one that wasn't outrageously priced (2.5x times the original price I bought it at). I ended up just selling my CPU and moving to a Sky Lake build.
Thank you for your reply. I believe the motherboards with LGA 1151 or 1150 won't support i5 3470 right? As the structure is totally different