Prices of Attraction Tickets, Meals, Groceries, etc ...

I'm using a friend's week in the Vistana Spa section a week from today and was curious about the current status of the collateral expenses. I'm thinking about picking up his timeshare interest and was reading about the renovations and some disgruntled posts about a steep increase in maintenance fees last year (like around 15 - 20%). My friend recommended buying disney, universal, sea world, etc ... tickets through the conciere service because of the great discounts, and the Sheraton site talks about the discounts as well, but the ticket prices stack up as follows:

Sea World site = Adults @ kid's prices if you book 5 days in advance ($275.80 for four) with second day free. Sheraton online ticket purchase = $303.73 to purch. the four tickets

Disney 4 day basic passes = adult @ $56.25 per day; child @ $48.00 per day Sheraton online Disney tickets (4 day basic) = adult @ $59.28; child @ $50.75

Universal park one day basic = $79.00 adult; $69.00 child Sheraton online Universal one day basic = $81.64 adult; $71.49 child

I know the prices aren't THAT different, but it makes me wonder whether the conciere service is viewed as a way of making up lost revenue through a mark up rather than a way of providing added value through group negotiated discounts ... if it is, then are the prices going up at the restaurants? Other services being nickel and dimed?

I'm looking forward to the trip and I understand the resort is beautiful, but I'd really appreciate any advice on discounts, prices info., etc ... any more seasoned Sheraton-goers would have to offer.