A couple from the All that glitters website look promising BUT I seem to recall that the vendor isn't reliable - apologies if I've got that wrong but I think you might need to do a search for them on this forum to see if people have been happy or not with their purchases.
Well I contacted them anyway to get some more info on a stone. I wanted a video of the color change and some additionnal pictures, since there are only 2 on the website. And while the guy seem very professionnal, he said that they don't have the equipment required to show the colors of the alexandrite on video, and that it looks terrible on an iphone.
But you can imagine I can't buy a stone if i only see 2 pictures, under 1 angle only.
So buying from there is not an option.