Free: Contests & Raffles.
2s and 3s are about as multipurpose as it gets.
I'd recommend patterning your gun with whatever chokes you have. What you find may surprise you. I've bought a few aftermarket chokes over the years but none have ever been worth the cost over factory chokes in my opinion.I find myself shooting an improved cylinder in my remington 1100 most of the time, usually with #2 shot.