Tesco deal haters click away now...
Tesco Extra (Prescot) had ION Quick Play LP USB Turntable for £12.25 - £49 online at Tesco Direct and also at Amazon. It was a white SEL (not the usual yellow for reductions) so could be available elsewhere.
It includes software to convert to MP3 and is powered by USB (cable and adaptor supplied if required). There is a line-level output via RCA plugs to play through an amp or powered speakers too.
5* review here: http://www.expertreviews.co.uk/accessories/50771/ion-quick-play-lp-review