Just got a pre-modded Wii with Wiikey from them this week, highly recomend them, I have had problems with similar sites before (gamesworlddirect.co.uk for example), so I was a bit weary to use them at first. I decided to give them a go as they took creditcards so I knew I would be insured anywayz and they have a 12 month warranty as well. Placed the order on monday at 2pm and it was delivered the next day before noon!
Out of the box it was brand new and had a Modchipfitters seal which invalidates the warranty if removed, I was a little annoyed at this 'cos I wanted to open it up to check if was a real Wiikey and not a clone or some other cheaper chip, but as the site is listed on the official Wiikey website I'll just have to trust it is a real Wiikey.
Set up the Wii and played an original and then tried a backup and both worked perfectly! Very pleased indeed, me and the girlfriend have been playing it all week!
If you've any other questions just let us know, hope I have been of some help