Welcome to the forum!
I have always bought my covers direct through SC. It was about $375 the last time but well worth it. It fits perfect, has all the reinforcements in the right places, and straps to hold the cover down to the trailer. They typically last me 6-7 years. If you like your interior, they are well worth the money.
As far as a prop is concerned, we need to know a little more. Boat length, engine make and HP, transmission reduction if any, and what you plan to do with the boat (i.e., slalom, wakeboard, cruise, how much weight/how many people?)
1992 Supra Mariah - Red
PCM 351HO 285hp - PCM 1.23:1 Transmission
OJ XMP 4 Blade CNC 13x15.5RH
"People do weird things to boats" -Unknown