If you decide to sell some let me know. I incubated some last year and ended up with nine males and two females. One started laying and sitting on her nest but something got her and the eggs so now I am down to one hen.
I know with chicken eggs you can incubate them for a few days and then candle to see if there's a chick developing or you could crack a couple and see if they are fertile (I believe speckled hen has posted some photos on the egglaying and chicken behavior board - they were stickied at the top last I checked). I imagine all this is true for guineas as well.