There's always the old tried and true Lotus parts services in the US:
Sports Car World
and a few others - those are just the ones off the top of my head that I've bought from in the past. They have been mostly suppliers of parts for the "older" Lotuses, and I doubt that they have much for the Elise - YET. I'm sure they will all support the Elise in the near future, but they just got here.
Most all of these companies have a web "presence", but you would do much better by just picking up the phone and talking to them. They are all a very knowledgeable, and very helpful. They will tell you what they have, and give suggestions if asked. Highly recommenced by the "old timers"...
For links to some of these, you can go to my web site for the Elan, or go to GGLC's web site and look for the links...