I installed a pair of seats from a 2000 or so Firefly/Geo Metro into my baja. They are compact and easy to install and were about $100 for the pair. Before I got that car finished, I stuck them in a Toyota 4x4 truck (really rough riding) and it really helped make that thing bearable.
If you want real suspension seats, call 250.374.7175 and ask about Corbeau Baja seats. They might still have some available. I bought a pair from them for about $200 each but I can't comment on comfort as I haven't used them yet.