www.farnell.com sell them, Im sure TheCheeseMan will be in here to tell you the codes you want for the sizes... you require... I think they are around £20 for a 2x20, but dont quote me on that one... The only draw back being you need to wire them up Which is a simple job if you have ever soldered before
For 30 bucks, you can get one at Case Etc. Here is a review on that kit. IMHO, there's too many friggin' wires for that serial connection--and it's solid core wire---better to have a serial ribbon cable. A lot neater and more flexible. EDIT: Whoa! My bad. That's a parallel kit. But the comment on the wires still applies...
£12 for a small 20x2 backlit that will fit in a floppy bay... I've grown tired of quoting codes though - ring farnell and ask for a catalogue, they're free and a really nice read r.