Based on some lens reviews since the A900 came out. I believe the Minolta version may be the one you want. The Sony version was developed before they went full frame sensor. While the Minolta version was back in the maxxum film generation. I have seen them on ebay for about 600-700.
Careful on condition for obvious no filter type lens.
I have used it on a a100 and it is a fantastic lens with fast focusing.
A700 w/VG, A100 w/VG
Minolta 50 1.7, 28 2.8, 80-200 2.8 G,
Tokina ATX Pro 28-80 2.8, Sigma 10-20 4-5.6, Vivitar Series1 17-35 3.5-5.6
Sony 1-F58AM, 1-F56AM 2-Fong Light Spheres
Bogen, Manfrotto 3245, 3216 mono's, 3001, 3021 tri's, 3245 head, Kaiden Kiwi+ Nodel Pano head
Alien Bees 2-1600, 2-800, 4-400
Macbook Pro unibody loaded
And 1/2 a garage of othe