$12K for CFI/II?!?! I think I spent around $5K for CFI/CFII/MEI.

As mentioned above, there is an airline or two that may interview you with those times. However, if you'd like to gain some flight instructing experience before moving on to a regional, I will endorse the above recommendation of going to an FBO or other school to finish your ratings.

If you are worried about finding a CFI job, don't be. There are plenty of jobs available. If you're willing to move, there are a couple of gigs out there that will pay you very handsomely for your labor. (About twice what you'd make 1st year at a regional.)

Dare I say this..... if Regional A is interviewing candidates with 250 hours and most others are interviewing candidates with significantly higher times, there is probably a reason why Regional A needs such low time to attract candidates. Do your research and make a decision based on what you'd like to get out of this career.