Hi Janet,
Here is great way to find any kind of plant you are looking for. Go to http://davesgarden.com/gwd/ and click on plant scout on the right. Then just put in the name or part of the name you are looking for. I searched for trollius there and found four different varietys at two different nurseries, both the nurseries listed are excellent, but if you wanted to check yourself just click on the nursery name and you can see how people reviewed it. I didn't find Alabaster for you, but hopefully this will be of some help.
Stacy

I am a big fan of trollius. I have never heard of a white variety before, but would love to have it! Do you know if 'Alabaster' is really white or more of a cream?

I think it is not difficult to start from seeds, so that might be another option for you. Thompson and Morgan usually carries seeds for the yellow varieties.

You can get trollius 'alabaster' from Daffodils and More' Dalton, Ma. They are $15 each and Dave ships them. I think the website is daffodilsandmore.com

Squires Country Gardens in Cambelleville, Ontario specializes in rare and unusual perennials. They grow well over 2000 varieties. Today I bought a Trollius Alabaster. It is beautiful pale lemony yellow. They also had species glads which look like little orchids with siberian iris type foliage and species impatiens (Impatien Glandulifera) among other gems.

Does Squires Country Gardens have a webpage I couldn't seem to find them on the web.