I have a Life Fitness recumbent bike similar to this model: www.fitnesssuperstore.com/Life-Fitness-950
It is rated up to 400 pounds and it's a good bike, but definitely not cheap. When I was shopping around I didn't see much that was under $1000 that was rated over 300 pounds and many of the cheaper ones are only rated for 200 or 250 and some are even less.
If you do decide to try a recumbent bike I'd advise getting a walk through model. I like the bike I got, but i'm short and have pain in my hips, so it's a task actually getting on the thing sometimes.