I'm still using an 120gb iPod Classic I picked up from Cash Convertors, seven or eight years ago.
The drive sometimes makes a ticking noise, but it still works, and still gets around 20 hours playback from a single charge.
Overall, it's been one of my better tech purchases - it's definitely been value for money, at least!
I occasionally debate buying a new battery and one of the SD adapter hacks (or, more likely, buying a pre-upgraded one off Ebay), as that'd probably keep me chugging along till the heatdeath of the universe...