Sweet Pea seeds

We went to a sweet pea show at the end of June and I came away with a few seeds to sow for next season. I want to sow them this year in root trainers as I think that will help to disturb the roots as little as possible, so I've had a count up of how many seeds I have and assuming that I use one seed per trainer I need about 150.
Now to do a little searching on the Internet to find the best place to get them.