Originally Posted by
maddmaxx
I suspect that some of your requirements are in conflict with each other. IMHO, adding suspension to a bicycle in that price range is not a good return on investment. It will amount to little more than a pogo spring and will add too much weight to your choice at the same time that its price costs you good components needed elsewhere.
I will add to this from MM- and from bcoppola- Rigid forks but with wider tyres will work better. If you get 26" wheels then you can go as wide as 2.0 on tyres that have just a bit of tread- they are called semislicks.
And if you have a back problem- Don't eliminate road bikes till you have tried one- The more stretched out ride position does help some backs.
So out to the shops and window shop- and test ride.