I have a Paezold Contrabass. They are very good. They have a strong first octave which is what you need and a full two octave range. They are also very easy to play as the wooden keys have finger "pads" that are placed in comfortable reach. Although the larger ones are cheaper than their round equivalents, they are not cheap. The bass and great bass versions have a wooden rod at the bottom so they will stand on the floor. I agree they need plenty of air down them, but their demands are not excessive. I was asthmatic as a child and don't have huge lung capacity but I can manage mine fine.

I think I have a sound sample on my computer. If not I'll make one and post it online so you can hear.

I use a neck strap with my regular bass and hold it to one side rather in the same manner as a bassoon.