I thought most of the 3V problems were on the 5.4. I haven't heard too much about issues with the 4.6, mine has 95K and I haven't done anything except change the plugs.
Anyway- I don't think I would ever actually buy anything with 200K on it, unless it was super cheap.
Such is the case with my Ranger, it had 172K on it when I got it (closing on 180K now- speedo is off due to bigger tires), BUT I got it for $800 with a blown up transmission and fixed it up. It was a former company vehicle and I don't think the 4.0 in it ever had any major work done either, all I've done with it is replace the plugs and fuel filter and change the oil.
2005 Mustang GT
CMS Stage 1 cams, Lito Tune, C&L Racer, CMDP, SR UDP, JBA LT's & o/r H, Magnaflow resonators, FRPP Touring AB, Koni STR.T, BMR springs, J&M upper/mount, BMR lowers & brackets, J&M pb, Steeda Tri-Ax
2009 Ranger XL SCab-4.0, auto, 4WD