Thank you guys for all the information. just to update you i met the guy with the intention of walking away if i'm not completely comfortable with the purchase. I met him in a residence address and asked him about the registration he mentioned earlier and he logged to a website called "bike register"
https://www.bikeregister.com and the bike was registered to his name with pictures of it. He put my name and email in the website and the bike was transferred immediately to my name which is cool. The price of the bike just got reduced today for 519 in
Halfords I don't know the original price but i bought it for 300. thank you everyone for helping really appreciate it.