You might not want to hear stories like this but there's a well known bluegrass band by the name of Mountain Heart. Their banjo player has only a thumb and the first finger on his left hand. He plays with his hand going over the top of the fretboard. And he plays as good or better as musicians with all five fingers.

I guess I'm saying don't give up hope just yet. If the desire is there you will succede. No need to sell the banjo now. It will still be sellable next year.