Having had a quick look round at least £25 a month seems to be the going rate, unless you are prepared to pay up something up front on the handset.
You should be looking at total cost of ownership though rather than focusing on the monthly cost, so make sure you add up all the costs over the life of the contract.
£22.50 a month if you can be arsed to claim cashback
http://www.e2save.com/mobile-phone/contract/blackberry/Blackberry-9700-Bold.html?tariffcode=D30JEAPR10
Having had a quick look round at least £25 a month seems to be the going rate, unless you are prepared to pay up something up front on the handset.
You should be looking at total cost of ownership though rather than focusing on the monthly cost, so make sure you add up all the costs over the life of the contract.