There is a paper somewhere (trying to fish out the link) about PhD program as a factor in job placement. It's a big deal. You should absolutely do what you love, but go into this with your eyes open. Depending on your field, placement can be incredibly competitive. Are you cognitive? Social? IO? Clinical? In IO you'll be fine. It's in demand and the pay is great. Clinical is in the middle (the impression I get is that the bottleneck is PhD entry, not employment, but it's not my field so grain of salt). Cog and social are ridiculously competitive. There just aren't enough tenure track jobs. You need a backup plan so you don't end up flipping burgers (or worse, teaching as an adjunct for no benefits and terrible pay). I'll post that link as soon as I find it.
This could fall into a few different fields: I/O is the obvious one, but positive psych is an emerging field that seems relevant here (you won't find many programs for it, but look up Seligman at Penn). Also, decision-making as it relates to money? I'm thinking cognitive (for decision-making in general) or even behavioral economics (there's quite a bit of overlap at some schools, and with your background this might be easier to break into).