If you can wait until you get to the UK, you can buy a PAYG phone with SIM from 99p - that's GBP 0.99, about $1.55, including tax - if you buy GBP 10 call credit, so from GBP 10.99 for phone, SIM and some call credit.

Try Carphone Warehouse - http://www.carphonewarehouse.com/pay...go/deal-finder

The 99p phone from CPW is an Alcatel OT 209. They have other phones from GBP 3.95. I use a perfectly acceptable Nokia 1661, which costs GBP 4.99 at CPW. All plus the GBP 10 top up. May prices may be slightly higher as there is a VAT increase from January 4.

Nokia phones at CPW are unlocked, not sure about the others.