I'm not sure where you'd go for transmissions for those particular cars. What I would recommend is looking up some automotive forums online for those two cars and do some searches on those forums for reputable online stores that sell transmissions.
"Big" parts such as complete engines or 'boxes are better bought offline....if you need a few sealer rings, then yes by all means hit the internet. But for big things?
I wouldn't trust it. Maybe Deeez knows a good site, tho.