CKU is exclusively a learning event not a shopping event. If you are not preregistered, you can not attend.
Your $350 fee registers you for 5 classes a day for 2 days (usually Friday & Saturday) and then also 1 evening class (in Boston's case - Thursday or Friday). There is also a one-day make'n'take day (in Boston - Thursday) where the sponsors of CKU (various scrapbook companies) have the students do projects.
Local scrapbook stores usually offer discounts and special make'n'takes for CKU students while CKU is going on - BUT the students go to the stores - the stores are not at the CKU event.
CK also promotes conventions that have classes and shopping. They were in Manchester NH in May. It sounds like this is more what you are interested in. There everything was paid for a la carte - classes were $10-12 each, vendor faire was $10 for the weekend, and evenig crops were $20-25 per night.
You may want to look into the KISS event in Waltham Ma in August.