If you're starting out with a collection then I'd frankly advise against purchasing physical CD's just to rip them. They take up space, get lost, get scratched, deteriorate over time... I'd purchase online but read up on the formats and on the point of diminishing returns. Some labels sell 'HD' versions at a premium but a) these take up much more space b) they're more expensive c) in some cases it's a downright scam and most of all d) the increased resolution offered by the 'highest' grade is essentially meaningless as either the rest of the gear can't usefully handle it or even if it can, it's physically impossible to hear a difference beyond a certain point (essentially, everything beyond standard rebook CD becomes iffy in the extreme).
Anyway, the one thing I personally wouldn't do is purchase physical CD's if you'll just end up ripping them and listening via your computer.