It really depends on what you'd call cheap. I'd vote for a cherry board. G80-3000 or G80-1800 if you want a smaller one. They are available e.g.
here in the UK. They have the G80-1800 only with black MX switches (Model Number L
PXXX) for £62.79 ex. VAT, and the G80-3000 with Blacks or Blues (Model Number L
SXXX) for around £52 ex. VAT. I would definitely prefer Blues for typing, but I bet your coworkers wouldn't be very happy. (On the other hand I know people who are using Buckling Spring Boards in the office without anybody complaining)