WSCA contract?

[dalee18]

What exactly is the wsca contract? I'm about to buy a 3XU through ibm's educational program for my state, and on the part where I select my state, I get these options:

Online PC store (WSCA contract #94-00151)
Promotions just for you
PCs for home employee purchases
Student and alumni PC purchases

I'm currently a student and the price for this model between the online pc store and the student and alumni pc purchases link is several hundred dollars difference. I'm confused about the wsca contract note after the online pc store link. There's nothing I can find to explain who is eligible to purchase under this contract, but the fact that the link is titled "online pc store" is a bit confusing to me. How does ibm verify your eligibility for educational pricing? I don't want to pay more than I need to, but I don't want to order under the wrong link and then get charged more down the line when they decide I wasn't eligible...