New lense for my K-x

[Trihame]

I am looking for a new lens for my Pentax K-x however I don't want to spend a gruntch of money because I would like to eventually upgrade the body and go with canon. Anyway, I have been looking at the 50mm f/1.4 prime and the 55 - 300mm lens. I don't know which one I would rather have because I just enjoy taking photographs of everthing and I could really use both. I may just buy both in time but what am I going to go with first? Telephoto or prime? I don't know but thats not really my question. My question is is does anyone know of a better K mount lens out there for a better alternative than either of these lenses that won't kill my pocket book? I already have the kit lens 18 - 55mm and the 50 - 200mm.