Need a few questions answered...

I remember seeing kang and kodos during halloween, but was never given the chance to get them. any way to get these items? or will i have to wait til it comes around again? thanks for the help.

Well, I got Kang with the Victorian UFO, and bought the ray gun to shoot down Kodos, who started flying about in her saucer shortly after Kang unlocked. They were limited to that event. If they are ever rereleased, it'll be next Halloween, but I rather doubt it, since Kang and the ray gun were both rereleases from Halloween 2012.
There's hope that Shauna will be released again in February, but episode tie-ins like swanky fish are less likely to see rerelease, unfortunately.