I did a lot of research on paint, MDF, and cabinet doors. They are a high use, often get banged up location so it's important that the paint is made of tough stuff. MDF is also super absorbent so it's important to use an excellent primer. I looked at General Paint and Benjamin Moore among other products and decided on the Benjamin Moore Advance line. This product is made specifically for cabinets - it goes on smoothly, is easy to clean up and still has low VOCs. I didn't track my time well (or my moms, or Jordans) on this project - but it took us a couple of weeks or so, in the evenings and mornings. The one drawback about this paint is that it has about a 16 hour dry time - we did two coats of primer and two coats of paint on both the fronts and backs - so many, many hours.
I will say that if you tackle something like this yourself BE CAREFUL OF DRIPS.
Sanding takes the most amount of time, and you're most likely to get them when you do the edges and the paint drips and settles on the underside. After a bit of trial and error we settled on painting the fronts/sides at the same time so any drips would be on the back of the doors, instead of the fronts.
This is my mom sanding like a boss.
What Did it Cost?
Including sanding, primer, paint and brushes. Painting cost us $303. We saved around $1,000 by doing this ourselves, and saved more than that by going with MDF over a solid wood door.