[LAU] USB interface for backing up old tracks mastered on cassette

Greetings everyone, my first post to LAU for about 15 years :) I'm looking for a USB interface for use with my Lenovo G500 laptop running Slackware 14.1.At this stage I'm primarily interested in backing up some old tracks that were originally mastered on metal cassette tape. I have no immediate plans for doing any serious audio production using this machine (although that might be a possibility in the future). I haven't bought a sound card since 2003 so I'm a bit out of touch with what is available these days, and what is supported on linux. A few people have recommended RME to me. After a very quick look around the web the cheapest option I've found is an RME Digiface for £320. So I guess the questions are: Is it worth forking out for an RME device, or is there something else out there that is a bit cheaper that will serve my current purpose? How about the M-Audio M-Track 2x2M? (approx £90) tbh I'm asking all this based on the assumption that the on board device isn't great without actually testing it :) many thanks, Jordan