Long zoom suggestions?

If you could find one, I couldn't recommend the Sigma AF 100-300mm F4 EX DG (IF) APO highly enough (I've used it for motorsport and aviation), but the best of the rest within your price range would arguably be the Tamron SP AF 70-300mm F/4-5.6 Di USD.  Used prices should be around your budget.

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Mark @ Sonolta * Photography