Which telephoto lens? (A100)

There seem to be several affordable telephoto lenses that can serve alongside the kit lens on the Song A100.

In order of price:

-Sony 75-300mm f/4.5-5.6 which can be had for about $200.

-Sigma 70-300mm f/4-5.6 which retails for slightly less than the Sony brand.

-Quantaray 70-300mm DI f/4-5.6, which can be had for $150

-Tamron 75-300mm f/4-5.6 which retails for even less than the Quantaray.

My question: has anyone compared these or had any first hand experience with their performance/IQ? I understand none of these are top-grade but would still like the best possible lens for the price range.

Thoughts?

-bK