My favourite real world place for books and the like (including great coffee and cake!) is Borders. But my favourite place for actually buying books is Amazon, because the selection and prices are generally very good.
For instance, the other day I ordered a couple of things from Amazon (well, the Amazon Marketplace) - a Kingdom Come TPB and Universe X Vol 1 TPB. Funnily, both involve 'alternate' futures of the two main superhero universes and Alex Ross. I loves me some Alex Ross (erm, you know what I mean).
The Universe X one was about £2.70 (+P&P) for an unused - i.e. new - book, which is quite some discount. But not as much of a discount that I got for the Kingdom Come book. That was only 1p. Yes, one penny! (plus postage and packaging of £2.75, mind you). Admittedly this was for a 'used' book that has some damage but still, that's a bargain.
Now, I actually already have issues 1, 3 and 4 of the Kingdom Come mini-series. At the time I didn't get issue 2 because I didn't realise this was a mini-series. I thought issue 1 of Kingdom Come was a one-shot. Although the ending of #1 seemed a little strange, I thought that that was it. Superman had reappeared to save the day from all those new, young and violent upstarts. Everything was going to be okay. End of story.
It wasn't until a few months later that I saw issue 3 in the comic shop. Of course, they'd sold out of issue 2 by then so I missed out. Suddenly, the 'ending' wasn't as strange any more because, of course, it wasn't actually the ending! I wished they'd made it more obvious that it was a 4 issue mini-series.
Anyway, at just 1p, I thought it worth getting the TPB to fill in the gap. I think it also has an additional epilogue at the end that wasn't in the original and perhaps a few other additional bits and bobs. I am slightly concerned about the condition, mind you, which was described as average and readable but with large creases on the front and back covers and in the pages themselves. But I'll see when I get it.
And for the price, it can't be bad.