You don't need a video service. It is easy to do yourself.
To get your VHS video into iMovie, look at the Canopus ADVC300. Audio and Video go in, FireWire comes out. It also comes with a nice Macintosh application that works flawlessly with iMovie 06 and iDVD 08 (not sure about iMovie 08).
The program that comes with the ADVC300 has some nice filters that can improve video and audio of the source material. The ADVC300 will take Audio and Video from any source and convert it to FireWire (iMovie will treat it like a camera).
http://www.canopus.com/products/ADVC300/index.php
There is also the ADVC110 less money but not as good.
http://www.canopus.com/products/ADVC110/index.php
If you don't want some of the audio, just unplug the audio cables or set the audio to zero in iMovie 06.
iMovie 06 is a free download to iLife 08 owners. (THEY WANT YOU TO HAVE IT!)
http://www.apple.com/support/downloads/imovieHD6.html
The differences between iMovie 06 and iMovie 08? I have found the below link to be helpful.
http://www.geethree.com/slick/imovie8.html