50MM lens choice

I had asked this in another thread, and I have searched but would like a more current opinion. I had purchased a Minolta 50MM 1.7 from KEH, but it has a back focus problem on my A65, and is going back. The few shots I took using manual focus, I was very impressed, even compared to my 16-50. My question is, since good copies of the Minolta seem to go for about $100 from KEH, and the Sony 50MM 1.8 is $125 until January 7th, would I be better of getting the Sony, or keep trying for a good copy of the Minolta and pass on the $25 Sony savings? What, if any, differences (besides build quality) will I see between the two lenses on the A65?
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Gary C.