I've had the K2 for some time now, and theres a few things I don't like about it. The main is that the aperture doesn't go under 4. Would a new lens be able to correct this? If not (and prices being considered) would switching to something like an A1 or Nikon 6000 series be my best bet? Please excuse my ignorance, and thanks in advance.

Are you refering to the Rebel K2? If so, then your max aperture is determined by your lens, not the camera. If you want to shoot wider than f/4 you will need a faster lens. If you're looking for a fast, inexpensive lens, check out the EF 50mm f/1.8 (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=12142&is=USA&addedTroughType=categoryNavigation). You can get a brand new one for $80, and the optics are great. I don't know what you're shooting, and what focal length you're looking for, but this is a very good, very inexpensive standard lens.