Prestige in the eyes of whom?
If your concern is being a viable candidate at a prestigious med school, then the most important things are GPA and MCAT and the legitimacy and rigor of your education and experiences.
In other words, if you can get accepted at a program like Goucher or Bryn Mawr, then you are taking a prestige path. If you don't have the numbers to compete for a prestigious postbac, then prestige isn't interesting in your med school candidacy.
Prestige isn't the issue with CC or online or other inexpensive postbac options. The issue is rigor, which usually shows up in your MCAT score and LORs. If you want to maximize your odds of getting accepted at a good, reputable med school, then don't consider the cost or convenience of your postbac as being the most important criteria.
Best of luck to you.