Hi all..
Ive just stepped up from a K100D to a K-7 and im looking at upgrading from my Tokina SZ-X 60-300 Zoom to something reasonably priced

before Avalon airshow next year..ive got a few shots from the K-7 at Brisbane's Riverfire that are what id consider keepers considering i spent the evening blundering about with a Push-Pull manual focus lens that had to be chopped up a lil so the P/R mount would work on my K100d and the K-7..
heres an example or three..(clickable thumbs, blackhawk is full sized, the other two are crops)
But i would like something within a similar focal length that works as an AF lens at a reasonable price (the Tokina only cost me $36AUD and serves me well except it is soft at 300mm when shooting distant aircraft) and i know that i wont match the value for money my SZ-X has given me... especially its sturdy all metal construction!
any help or suggestions would be great, thanks..however due to my not so good experiences with the sigma 18-50 kit Lens from the K100d..id sooner take a slight step back from that brand..