Originally posted by Piotrek K I tested one more lens today inspired by this thread and maybe found good one that could be purchased really cheap (I bought my copy for about 45 USD including adaptall mount and international shipping).
This is Tamron SP Adaptall 60 - 300 23A (3.8 - 5.4) which I tested today at 300/5.4 with the original Q fitted with generic adapter on the tripod.
The Tamron 23A is the "bang for the buck" king of the tele zooms, as far as I'm concerned. It's roughly equal in IQ to the Pentax DA 55-300 at a fraction of the cost. Plus, it has a really useful macro mode. I have the DA 55-300 and still use the Tamron from time to time.