The wine museum is a VQA tasting room (2 wines per day) that sells selected wines from 90 of approximately 110 VQA wineries from around the province. Some wines appear to be even cheaper than at teh winery. None are more expensive as far as I could tell (some wines are available at BCLCB at the same price).
Worth a visit if you have any particular wines that you would like to purchase that are not available elsewhere. For example - the JOIE Noble Blend used to be available only at Naramata Bench Winery or at selected restaurants.