Experiment running since February. Thesis: abandoned small sites with real link profiles are cheaper than building from scratch, and most of them died from neglect rather than penalties.
Bought so far: 10 sites, total spend $4,310
Rebuilt: 6
Recovered to pre-decline traffic: 3
Dead for good: 2 (both had link profiles I should have looked at harder)
Full spreadsheet of what each cost and where it is now, updating monthly. The interesting finding is that rebuild cost is wildly more predictable than recovery time.
Currently: 14 sites, 11 of them bad.