I'm with you. Absolute cost per GB (regardless of performance) is still a huge barrier for me.Still waiting for a $100 SSD with TRIM support that's over 80GB (and has decent performance).
I could be considered an outlier.... I'm really quite happy with my hard drive performance. Currently using a 1.5TB WD GreenPower drive for my OS. Rarely do a full shut down or reboot, mostly just put the system to sleep when it's not being used.
Now, for a laptop, having an SSD would be much better I think. Not sure what battery life improvement you get, but I'd imagine it's something. Plus, you shut down and start up much more often, so performance there would be noticeable.
Whether laptop or desktop, the ssd is the best visible upgrade one can get for a system. Its a huge visible difference all around.