Very nice, I'm a lane defence, buying whole bunches of units, kind of fan so this was very much up my alley.
I think the cost of units and upgrades has been mentioned a few times :P (I never got to unlock a new unit)
It's got a very nice aesthetic, blocky characters will always make me think of minecraft.
Did find myself clicking on a lane but not spawning anything because I was accidentally clicking on a unit.
Quite enjoyable, Good job!