I use a Cherry mini keyboard (G84-4100PPAUS) that you can get used on eBay for $10. + $10 shipping. and I use a USB keypad/calculator with it for when I have to balance the checkbook, etc. I like that as it keeps my trackball right next to the home row and you can switch to calc mode and patch the result into a field on the screen - pretty neat. You can also unplug it and use it as a stand-alone calculator - very flexible. I have some of the keypads (two models) for sale in my FS/T thread which is linked below.
Bill