If you try Googling "suppliers of Elegance tomato seeds and plants" you may find some sources.
Also, if you register on the forum of the Kitchen Garden Website, they have a Seedswap facility and there may be somebody these who can help you out with a few seeds. If you can succeed in growing some, save some of the seeds and dry them out for sowing the following season.
Look at the bottom of the page. It seems that Dobies might be supplying them so perhaps you could check out their website to see if you can order them independently.
Had a bit of a goose chase to find this but go to this Sutton website link and look at the bottom of the page for the Tomato Collection. Open the box and check the options.
But it's a jolly expensive way of buying three tomato plants !