50mm 1.8 is cause of err99

Long story short, I have determined that my 50mm 1.8 might be dying. When I put it on the camera, I get err 99 every so often. When it happens, it seems that the aperture blades get stuck in the "closed down" position. I have to remove and re-attach the lens to clear it.

Anyway, I guess my real question is should I just replace it or consider the 1.4 version. USD $80 is a pretty good price, but I think I'm looking for someone to convince me that i SHOULD get the 1.4. Also, what about trying to find a 1.8 mk I on ebay? anyone care to share mk I / ebay experiences?

I do find myself using the 50mm alot because of the 1.8 even though I wish it were wider. I do have the 85 1.8 but I only use that lens occasionally (like indoor basketball).

--
Beauty is in the eye of the photographer