Originally posted by Chaim The F50/1.7 or FA50/1.7 are a nice option for a used lens. I understand they are both long discontinued and sell as used quite cheap (about $50 for the F).
Not sure where you are located at but $50 for an F 50 is not going to happen, or if it does you got a incredible deal. And the 'A' models usually go for over $100, maybe $125. So if you can get one for $50 buy a bunch and resell.
Also, keep in mind that "not incredibly sharp wide open" is not the same as unusable or even unacceptable. It just means the reviewer can see a difference. Only you know how sharp is has to be to make you happy, but 'sharp' is not a yes/no characteristic. It is gradual change from something perceived as 'sharp' to something perceived as 'less sharp'.
If you have the opportunity, try a few different lenses in a shop, or borrow or rent one to try and see for yourself.