If u can afford n hav e patience,then wait for minolta new 70-200 f2.8 G SSM 'D' lens (at least $1950) to arrive in S'pore.Original lenses give u the best performance.If not consider buy minolta 70-210 f4 from Andylee as suggested Also i heard it comes with a kenko 2X teleconverter.
The latest Sigma lenses dont support Minolta AF mount. Since Sigma is not keen to do business with Minolta,why should we buy from it(Sigma).This is jus my personal opinion. In this case "Customer is always rite".
On e other hand,i really hope Sigma HSM and OS len can soon be compatitible with Minolta SLR camera soon.