Cheapest/Fastest way to get 12 CR?

[joben]

Hi all, 

Bit of a cross post but here's the short version - i've applied to a master's program but my undergrad GPA is too low. I've been told I can take 12 credit hours "non-degree seeking" at the same institution OR 12 "graduate level" credit hours elsewhere and provided my GPA is high enough in either of those routes I'll have my admission approved. They need to be RA credits and actual graded classes. 

The program I'm looking at is in social work, so something along those lines or semi-adjacent to it would probably be my preference, but if there's something else much faster and/or cheaper I wouldn't be too picky about it. Any and all guidance is welcome!