John Craig-Limit Engineering. I was pleased with their service and I got the kit in just a few days. They have always answered any of my questions and they seem to know their stuff. It was about $95 shipped but it has been over a year so prices may have changed.
Not to take away a sale from a quality vendor like Limit but you can find rebuild kits all over the internet for under $75.00. As a matter of fact there is probally one on eBay right now for under $50. Use T03 in your search. I would use Limit if you are unsure of what type of seal you have.
I would suggest sending it out. Yes you can rebuild it your self for the "$75" but do you know what you are looking at. Does the shaft need to be turned, can you clean the housing properly???? Consider the abuse the turbo take... ... send it over to John and Chopper. When you get it back it looks new. If you want to save a few bucks, just send them the CART and keep the housings with you. Only a suggestion.