From my own ebaying and lens purchases I can suggest:
-takumar zooms not worth much;
- 50mm macro takumar typically goes for £50-80;
- takumar 55mm 1.8 typically around 20-30;
- super takumar 24mm f3.5 not sure, pentax 24's usually bid up well.
smc pentax-a 20mm f/2.8 ?
smc pentax-a* 200mm f4 macro ed - you might solicit professional advice on this one
smc pentax-a* 300mm f4 - two sold for ~£ 200 odd over xmas/new year
smc pentax m 400mm f/5.6- around a £150
It's always a bit of a dilemma as to whether to list as a BIN or auction on ebay. BIN's work best if you have a good idea of the value - you can then guarantee getting it. Auctions always have the possibility of disapponting (occasionally jackpot'ing!) . Auctions: take the time and trouble to describe carefully, with the best pics you can do (worth using inkfrog or auctiva image hosting for these), 10 day listings finishing weekend evening time.