Value only IF "X"

What I'm trying to do is return the lowest value of any "checked" row.
(Sorry for the crudeness of my chart, I'm new to this...)

A for the check mark (in this case "X")
B for the name of the training class
C for the cost of the training class

_____A__________B___________C
1____X_________SWAT_______$1000
2______________RIFLE________ $800
3____X_________PISTOL_______$600
4____X_________TASER_______ $400
5______________ BIKE________ $250
6
7__________________________ $400

I need C7 to return the lowest cost of only the training attended, in this case "TASER" at $400. I've tried so many combinations of IF AND VLOOKUP but I always get stuck on returning only the LOWEST "Checked" row...

Any help would be great.