What would be the most reliable, cheap device to run spotify offline?

[BLB0975]

So I do not want to fill up my phones space with music and I dont want to keep using data to play music so I decided to get a device to be used mainly for spotify. My first idea was to look towards old ipod touches... but then i quickly realized spotify will not run on a 1st gen ipod touch because it cannot update to 4.0. Right now im contemplating 2nd generation ipod touch but my concern is will the 2nd generation just suffer the same fate as the 1st if spoify updates to an ios that the 2nd gen cannot support?

What is the best cheap device that has about 8-16 gb for spotify offline?