a Iphone 3G 8GB for about 140 pounds second hand (Perfect condition for that price too... or you have been scammed) Then go with O2 and its a 10'er a month for unlimited texts and unlimited internet
Theres one option
unless your after a nice camera... i think there 2megapixel on the phone
But yeah maybe have you considered doing a contract? Ive never really gone with a contract before though myself, i hate being tied up to anything!
On the websites they normally do the whole spec comparing thing ready for you
Hope i was kind of useful in a little way haha!