I realize my response is a little late, sorry.
I believe Sherwin Williams paint stores make use of Pantone colors, so you should be able to get paint chips from there if you don't already have them. Home Depot advertizes that they will match any color (let's face it, most large stores have the latest paint matching equipment). So even if you don't have a paint chip, if you can get your hands on a souvenir from the school, you could take that to the paint dept.
I think it's wonderful that you are attempting to match the school colors exactly. If you are unsure of your chips, you could call the school. There must be someone who can give you a person to contact for help if you haven't already found enough help from the nice people here. If indeed there is a contact affiliated with the school's merchandising, they might also know where you can get your hands on fabric specifically made/dyed for the school products. I assume that would be solid colors.
Good luck!