I can definitely see where you are coming from Chesilbeach! I have quite a large number of books but many of them are not ones that I would read again and so just take up a lot of room (but I can't seem to part with them).
I guess with an ereader you could still have them but without them taking up so much room! I would still buy books though, but as you say be more selective! Perhaps buy particularly nice copies, special editions etc, wait for box sets come out! I particularly love the new covers on the F Scott Fitzgerald annivesary editions being published by penguin.
http://www.creativereview.co.uk/cr-blog/2010/august/penguin-classics-scott-fitzgerald-bickford-smith
I have been to a number of book signings recently but can't bring myself to read the signed copies, so try to get them from the library or in a charity shop so that they don't cost me so much money. The problem with the library is that they don't always have a lot of copies or they are all out. Charity shops, whilst an excellent source of books, can't be guaranteed to have what you want and I am rather impatient. The ereader would seem to solve this particular issue. Hmmmmmmm, what to do!?!