Apple iPhone 4 32GB on 3 network ?

Selling my iPhone 4 32GB as I just upgraded to an iPhone 5. It is locked to 3 network but can be unlocked for cheap. It is boxed and comes with everything it originally came with including, box, unused earphones, charger: mains adapter and USB cable, leaflets and sim opener tool. I have purchased a CheckMend report for this phone which checks the full history of the phone and it has no record of it being blocked or reported lost or stolen or subject to warranty claim so for reassurance I will pass the certificate to the buyer. Looking for 220 which is a bargain considering I bought it for 400 a few years ago! Any questions please ask!