My Tamron 70-300mm f/4-5.6 LD Di is very decent and a mint copy only cost me 80 dollars. Sharpness is pretty good, I think, and color rendering is not quite as good as Pentax lenses but it's something you can work with in PP. Also, it's a full frame lens. It gets a bit softer towards 300mm but still very useable - and good at f8. At around 200 it's still very sharp. Even 270mm looks pretty good to me.
Earlier versions of this lens had tons of purple fringing but I find that this Di version (coatings for digital sensors) pretty much solves the issue. Also, the AF hunts in low light so focusing manually is necessary sometimes, but it's not bad to MF this lens.
For low light or when I don't need AF I have a SMC Pentax-A 70-210mm f4 which is a good lens wide open and very sharp at f/5.6 throughout the range. Colors are wonderful, to me at least. It even doubles as my portrait lens sometimes, it's got some magic at 70-100mm for someone like me who's never had limiteds or * lenses. It can usually be had for around 70 dollars. Downside is manual focus (it's pretty easy actually), and purple fringing is worse than the aforementioned Tamron.
That would be my suggestion for low budget tele work under 200 dollars - just combine these two lenses, they'll both still probably be lighter than that 67 monster