For dove/quail and normal upland, you’re not going to see much difference in range between a 20 & 28. It’s similar to the 16/12ga comparison. If you’re in that correct load weight range for either 3/4-1oz, there’s not going to be a lot of difference. Plenty even claim a 28 is better than a 20, due to gun weight and balance. I don’t disagree. Until you get to 3” charge weights, the 28 is far closer to a 20, and nothing like a 410.

As for shells, they’re like a 16.....deals online, and the occasional deal local, and just stock up. For a while, Cabelas Herters 16 and 28s were priced the same as 20 and 12 per box. I bought the snot out of them (16s). Good cheddite hulls for loading, too. Local hardware store did the same thing one time before dove season. I bought ALL their estate 16s at <$6/box. They had 28s same price, too.