Buffy Season 5 comes out Tuesday!
Or you can get the very reasonably priced Seasons 1-4 boxed set.
And, you can watch them both on this Norcent DP-300 DVD player, currently selling for the low low price of $29.99 after $10 mail-in rebate. This is the one I own. It's great because it plays all formats (mp3, VCD, etc...) and it also has a built in PAL/NTSC converter so you can definitely watch all region free international DVDs. In addition, at least on the version I have (which may have changed, so I can't guarantee), there's a simple hack using the remote which will disable the region coding system.