I must say C2 Diluted whilst drying the car is superb. Used it on the car last nick. Proper slick.
If you're looking for a cheap QD that's nice FK425 is pretty cheap. Adds gloss and a bit of protection.
If you're using C2 you really should be topping with diluted C2, nano products work better when used with other products so the beading and sheeting performance will still be the same, if you know what I mean.
What will you be using the QD for, whilst drying? After drying? Just a gloss enhancer or a proper top up product?