Yes, I've never found front-door type vivs except for the really expensive custom jobs, home-made enclosures, and one other place.
www.glasscages.com sell front-sliding-door vivs in the larger sizes at pretty reasonable prices too.
I've bought 2 of the 48x18x17 tanks from them, and they've got even bigger ones available.
***IF you're in an area that they will deliver to, otherwise I'm sure regular shipping costs would destroy you.***
I'm sure there are other places that sell similar...look for actual aquarium shops, ones that build custom jobs.