Dental Photography Beginner/Budget Setup

I am a dentist looking for a budget setup to take before/after pictures and document some of my cases.

I’m planning on getting the following: 1. Tamron SP AF 90mm f/2.8 Macro…..~$250 2. Ring flash from Amazon….~$70

I’d like to pick up a used body for under $150 in the Nikon family. There are so many models that I’m having a hard time choosing. D40-D90, D3000-D3200, D5000, D200, D300 all appear to be sub $150 on the used marketplace (most are even sub $100). Is there any one model in particular that would be better suited for my needs?

I suspect that as I get into photography more, I’ll want to upgrade lenses, flashes, etc. Right now I’m just trying to keep the cost down and get my feet wet. Thanks in advance