Honestly to save any hassle with sleeping and waking your machine my advice would be to build your own using a bluetooth module from an old mac.
I,ve built my own after buying three usb modules, which in fairness did work with my bluetooth keyboard and mouse but i just wanted to be able to wake my machine with the mouse!
I have a D-Link DBT-120 vB4 which worked perfectly apart from wake from sleep.
Belkin Mini F8T016ng which woke from sleep but you had to unplug then reinsert to get mouse gestures and proper keyboard functions going again.
And finally Trust BT-2400p Item Number 15542 same problems as the Belkin, and this is with modified kexts.
You can flash the D-Link i think, but i don't have access to an older mac.
Modified mac bluetooth is the only way to go, if you want proper wake from sleep.
But if you don't mind using your power button to wake i have the D-Link DBT120 vB4 for sale.
Up to you.