Aviation International @ Guelph Airport

Aviation International is a flight school that runs the Guelph airport and happens to sell tie-down spots and 100LL fuel to transients, but it is definitely not a full FBO. According to the woman on the phone, tie-downs on the grass are $7/night, and you have to move your plane to and from the fuel pumps yourself (though they do the actual fueling). They have no arrangements with rental-car companies, not even a key drop-off.

For full FBO service (e.g. leave a fuel order and walk into your waiting rental car), you can fly into Waterloo (YKF) 10 nm/18km away, but you'll pay a bit more money.