Does that mean I have to set up separate "Products" for Item 1/Price A and Item 1/Price B? That means they will both show up as part of the "category," so each Product shows up two or more times.

Perhaps your advice still applies, but I can't figure out how to set up and Attribute with up to four values, each value specific to the Product. I am definitely confused by the Attribute Manager page, but I can't figure out how to make this happen.

Total of about 40 Products, with 2 to 4 prices for each, total of about 80 to 160 different "Product/Size" pairs.