Help Buying iphone 4 - o2

hi iam trying to buy an iphone 4 on o2 network
from the well known ******* site.
i want it on pay as you go.
is there anyway if the seller gives me any info
i can check to see if the phone was bought on payg.
there seems to be that many that people are selling
are all on upgrdes.
any help would be appreciated as i dont want to buy
a phone and have it cut off 3/4 weeks down the road.

cheers paddyboy.

I very much doubt you will get one as Pay as you God mate as I got mine on contract if you get it as Pay as you go it will set you back quite a bit however it is a great phone to have even better when you jail break it try buying online from other sources and see what you find but beware of clones as they are loads around these days.