Hi, @Kim Handelman- a few thoughts on what else to consider. First, what's the market like for condos in Madison? They're a pretty slow sell here in southeastern CT. Do you have Days on Market included in your comps? Seeing as you plan to wholesale it, do you know any buyers who flip or otherwise invest in condos?
It's hard to tell whether the ARV is accurate because I don't know whether the comps are coming from the same building, similar area, etc. Here in East Lyme, which is not as affluent as Madison but still considered an upscale town, the condo complexes can vary widely. You really need to know the nitty-gritty about each.
You mentioned that it had flooded during Hurricane Sandy - could be a big red flag. Are potential end buyers going to purchase a property that flooded? How about the cost of insurance?
And finally, concerning the HOA, I personally would view it like taxes: if I bought it low enough and the monthly payment makes sense, then who cares? However, many buyers do balk at these things. But if $650 is aligned with similar condos, it might not matter so much. How does it compare to the HOAs of your comps?
Hope that helps. I'm not trying to talk you out of taking action, just pointing out some things that caught my eye! Good luck!