Yeah I just started buying CDs again. Check out some used record stores, they usually have a decent selection and often used CDs are cheaper than iTunes (and better quality). I have a couple albums from HDTracks, one of them sounds noticeably better than 16/44.1 (Fleetwood Mac - Rumours), the other doesn't sound much better (Norah Jones - Come Away With Me), so it may be hit or miss.
Careful with HD Tracks. Their sources are suspect for some of their stuff. Come Away With Me's CD release wasn't near as good as the SACD or any of the LP cuts.
I'd bet the HD Tracks downloads were sourced from the CD if it doesn't specify and doesn't sound better.