Can I replace the mouse that came with my keyboard combo?

I bought the Logitech mk270 wireless keyboard/mouse combo. I like the keyboard,
but I dislike the amount of force required to click the wheel on the mouse. I can buy
a separate wireless mouse, but I'd hate to have to use a second USB port for a mouse.
Are there Logitech wireless mouse models available that I could get to work with the
unifying receiver for my keyboard?

As this is a Unifying system, you can buy any Unifying mouse and use the same receiver.
You just have to pair the new mouse with the old receiver.