My second post was for the second SMP at Loyola's School of Medicine not the MAMS based in Loyola's Biology Department. That's what I was referring to regarding not needing the MCAT for admission. Did you check it out? Also, with the Loyola programs if you do well, you are guaranteed an interview at Loyola's Stritch School of Medicine.
http://ssom.luc.edu/physio/education/ms/
Most post bac programs will run you anywhere from 26K (Northwestern's certificate program) to 60K and up.
Did you check out the Post Bac FAQs sticky thread in this forum? I'd rather have a Master's degree than a post-bac certificate if I was planning on shelling out any kind of cash to boost my GPA.
I'm not an AdCom nor do I know your extracurriculars, languages, volunteer work, or racial background so I can only offer one person's opinion here. A person of non-Asian and non-White descent and/or an extremely disadvantaged background might have a better shot with your GPA and whatever MCAT score at applying this cycle.
Also, FYI, I think the MCAT uses a different system now, I think a new good score is somewhere in the 525 range but I could be wrong ---- anyway, it's no longer the same range.
Since you've stated you want to focus on a Chicago school, I believe there are 7 med schools (M.D., not D.O.) in the Chicago area. It might behoove you to check out their admissions requirements and a profile of the stats of the matriculating class to see where you need to be.
If money is a factor, then just take the few upper level classes you need boost the GPA and fill in any pre-reqs needed. Take them as a Student-at-Large at the University of Chicago, Northwestern, or Loyola (you can take classes as a visiting student at ANY school, btw. Rush, UIC, Chicago State, NEIU, Concordia, Dominican, etc.) and pay for an MCAT class at Kaplan or wherever, since it seems the MCAT is what you probably need to focus on.
If Post-Bac is what you want, be advised both Northwestern and Loyola both state their certificate programs are designed for students with no science background. SMP would probably be your best bet if you want a formalized post-bac type program.
However, Dominican University has an interesting type of Post-Bac (it's $30,600) - where you can get a second bachelor's in BioMedical Sciences in a year and take upper division classes. Same with North Park University.
Good luck.