I got the name of Newmarket Transformers (
www.newmarket-transformers.co.uk) from someone on this site, and I just wanted to let everyone know that I finally ordered my transformer. I brought my Cuisinart food processor and my KitchenAid mixer with me. Because the food processor had a 625W motor, I had to go with the 1000W step-down transformer (meaning it can handle up to 1000W, and converts both the voltage and the frequency). I got the one with the case.
The thing is
heavy! It has two plug holes on the front and a handle on the top to make moving it easier. It works wonderfully, and I've had the mixer and the food processor in use multiple times since it arrived. I paid £74, including shipping and VAT, and it was delivered quite quickly. The only problem I had was that paypal wasn't set up to allow me to order to UK addresses, so I had to phone in my credit card info. And the person who takes credit card info is not in the office very often. But you can leave your number and they'll call you back.
I am glad that I brought these appliances with me, and I feel that the cost of shipping them, plus the cost of the transformer was still a lot less than the cost of replacing them.