Let me ask - Would you consider a $10 keyboard as cheap?
How many would you need? Two, maybe three?
Gona take up a lot of room.
You might want to consider buying two mini Bluetooth keyboards.
Here's one for only $13. And it's only 11.6 x 5.1 x 1 inches. Lets just call it one foot wide. Two feet of desk space for both of them.
Are you willing to have something a lot better that costs around $50 - $60?
Logitech G13 Programmable Gameboard with LCD Display
It's basically three keyboards in one, with a hat switch, that works with Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10. I know that it works with Win 10, cause I just re-tried it after a long tome.
Here's the
Manual if you're interested.
Not counting macros, you can have as many as 84 buttons by using one of three shift keys.
It comes with an FSX profile, but creating a Prepar3d profile and copying the FSX profile over is easy.
The only bad thing is that SPAD.neXt doesn't recognize it. On the other hand, that would free up any other buttons to be dedicated to SPAD.neXt.
As an added bonus, you can program the keys to light up to match the function/profile that you're using.
But WAIT! There's more!
There's a very small, and free, program called
HIDMacros. This program WILL recognize each different keyboard, and let you assign anything assignable to any key on that keyboard.
One of the problems with using most keyboards is the they all treat the numeric keypad as just that, a numeric keypad. They don't ley you actually re-program the numeric keys. If you plug a numeric keypad into your computer, both FSX & Prepar3ed treat it as the same EXACT numeric keypad.
Except that
HIDMacros DOES let you re-program them. You can set up as many numeric keypads as you want, and
HIDMacros will treat them all as different keypads for programming sake.
This is a numeric keypad that I set up years ago to program an aircrafts GPS.
I mounted it on my CH Product yoke, with Velcro, so that it wouldn't move around.
If you're a little handy, you could buy a box like
this (for $18.50), and turn it into a "button/switch box that SPAD.neXt can easily work with.
You'll also want a
bag of buttons (20 for$11.24)
And a
Teensy 3.2 Arduino for $24.55 to control it all.
This is how Prepar3d sees the Teensy 3.2
Will 32 buttons be enough? If not, you can set it up to control MUCH more.
Read
Arduino controler to get an idea of what is possible.
For inspiration, this is one of the Arduino switch boxes that I found on the internet. The "cover" was printed on a color printer and taped in place.
Here's another Arduino box with a printed "cover".
How far you go is up to you.