Need affordable prime lens

Hey, Lex! In my humble opinion, just about any legacy lens from a name-brand manufacturer (Pentax, Konica/Minolta, Canon, Nikon, etc.) will serve you well.

Despite the near endless obsession in the forum about the technical aspects of this or that lens compared to that or another lens, unless the lens is an absolute dog, you're never (or rarely) going to be able to discern any significant differences between any of the decent lenses in most shooting situations.

Any number of other factors will generally outweigh/overpower/obscure any optical characteristics of any decent lens—your technique (holding the camera steady, ability to focus precisely, etc.), subject movement, lighting, composition, etc. All these factors will have far more of an effect on your images than any relatively minute differences in lenses.

If you're interested in Minolta in particular, Here is some good information about the Minolta lens pedigree.

I'd go with whatever decent (name brand), fast (f 1.4 or 1.8) lens you can find for a price you want to pay. Minolta f1.4 50mms can be found for under $100, at least in the U.S.

As for adapters, there's been considerable discussion on the forum in recent weeks/months, so if you do a search, you can check those out.

God luck!