Seats
For seats there are a few options to chose from.
You can buy real airliner seats
(even if not the same type as yours, it's better than nothing, right?)
You can try to find car seats
(and mod them if you want)
Or you can build a seat yourself
Other seat issues
add some vibration to your flight:
The seat has speakers - a car woofer speaker would work well 
- put a foam cushion on top and it makes a pretty realistic rumble that adds much to the feel. The simulator then has "tweeter" PC desktop speakers (those matchbox sized ones) on the top of the back wall of the cockpit for the high end of the sound spectrum. So rain rattling on the roof sounds real while the rumbles make your butt move. Try a thunderstorm.. 
Now, the simulator has curtains as doors so it is completely separated from the outside world in terms of visual references, everything you see and hear is the simulator. A hand-flown IFR approach on minimum weather in a single engine light plane sim is scary enough - now, I did this with a friend and used the "major thunderstorm" weather theme.. If something can feel scary in a simulator, that was it..
anyone has info on rails ?:
Car seats usually have built in adjustment rails so you dont need to make your pedals adjustable... - then again, if you always fly yourself, what do you need rails for? :)
Quite simply really .. to move your chair backwards to get out of the pit .. F50 doesn't have the "slide to the side" like in Boeings but I would like to have bended rails though (--PV8)
pls fill out this gap!
See here what Stephen did:
to
These are regular shelf rails. The U-shaped kind that you screw to the wall and then hang in the board holders to make up your shelf. Stephen used two of them, one riding in the other. Like this ASCII diagram:
|---| | || | |___|
This is a very cheap way to get adjustable seats.
You might also be able to use some heavy duty drawer slides. They might need something to 'set' the position so the seat doesn't slide around once adjusted.
--Manuel