MP3 album buy/download

I cannot find anywhere that does this - it all seems per song/have poor selection. Is it because it would discourage CD sales?
I'm thinking of buying an iPod but if it means continuing to buy CD's and then convert them then I'm not so sure as I'd like to use the ipod as my main music centre at home also, thus getting rid of the pesky cases and attendant search problems.I also realise there would be a sacrifice in sound quality but (I think) I'd be happy with the trade off.
Any thoughts much app.
j