The G25 is a top piece of kit - What game / platform will you be using it for?
ebay is usually a good place to start looking - you may be luck y and find someone has a complete setup for sale!
I managed to pick up the gameracer pro seat with the G25. The baseplate for the pedals could have been a bit bigger and at a lower angle than it is. Stay away from the original playseat, the G25 pedals dont fit on it at all, unless you prepared to modify it.