i have always used cduniverse. but the fact they put the contents and value on the package (And wont change it) has meant that the last three times i have been really done by customs. I mean £9.50 on a $45 game is out of order! Anyway I have used MOVIETYME for dvd's and they now look like they are doing GAMES. All import gamecube games are £34.99 and include free delivery in 4-10 days. I have never had to pay import duty on their dvd's so perhaps I will have better luck with them for games than cduniverse. www.movietyme.com
CD-WOW are doing console games now, £31.99 per game, the dearest was £34 i think and that was only one.
if you can wait a little longer then dvdboxoffice.com works a treat. In fact my copy of Mario Sunshine for the GC arrive in under 7 days