the 2008 sheng cake is about $4.00 per 100g shipped. The shou is $25.00 for 100g. I think the point is it is really overpriced. You're right that they are not completely comparable, but the quality of either of them makes the year/type moot.
here is a eminently drinkable Dayi 7262 for $6.30 per 100 g. The whole cake costs less shipped than the 100g the OP bought.http://www.ebay.com/itm/Menghai-Dayi-7262-Puer-Cake-2010-357g-Ripe-/300438970761?pt=LH_DefaultDomain_0&hash=item45f38ee189
(no idea if the seller is good or bad, just a random ebay listing)
Supporting local stores is great if you can go in and drink a few teas, talk to the owner who is intelligent about tea, and pay a small premium for this privilege. However, there is a point where you can get such better selection and price online, that if the local store is so far away in terms of price and quality, you go and buy online.