Reporting back because people asked me to when I bought it in February.
In-content link on a page that gets real search traffic, decent site in my niche, owner wanted $180 a month rather than a one-off and I took it because I couldn't afford the $2,400 he wanted to sell it outright.
Target page was position 22 when it went live. Best it reached was 11, in about week seven, and it sat between 11 and 14 for the rest of the six months. I built nothing else at that page in the window, though I did publish elsewhere on the site, so it isn't clean.
Stopped paying on the 1st of September. Total spend $1,080.
The part I can't work out is whether renting was stupid. $1,080 for six months at position 12ish, versus $2,400 for the same thing permanently — except permanent apparently means until he redesigns.