Hmmmm ,not mnuch of an upgrade ,there are different "GF2 MX" there is a mx 200 (junk not much faster then your ultra) then a MX which would be good ,$30 would be fine trade ,then MX400 ,then 64mb GFMX.
Why dont you go to Pricewatch.com and price an Ultra ,and price whatever model GF2mx he is trading and pay the difference.
And as far as beat-up?????? I plug them in ,either they work or they dont work ,I would love to see what the video looks like on a "beat-up" video car, I have never experienced this ,I have overclocked my cards heavily ,but the video 3d/23 is superb ,even moreso if ran at default clocks.