Well, what I did was but some relays, capacitors and some "cheap" switches. Wired it all up, and it worked great.
The only major flaw in all this was trying to get CTRL- type switches to work. However I managed to keep what I needed in single keystrokes.
On the subject of reaction time, I noticed none. It worked great.
As for the switches costing alot, I guess it comes down to what you want, or aspire to want. If it is a full blown life-like sim, then money should not be a great problem for you.. Also, in that light, You are probably better off looking down the road to an EPIC system or Hangstrom cards.
To each their own, and best of luck with yours :)
Ben