What Price Food?

In my random explorations of the city, I sometimes grab a quick bite to eat at whatever place looks nice nearby. In these local restaurants/stands, I'm sometimes forced to order food using the same mechanism KM used to use with Thai Kitchen (blindly blurting out menu numbers on the phone).
One way to control how much and what kind of food I get is to compare menu prices. Items that are listed in the same section of a menu are generally the same kind of food. Prices that are close to each other generally give an indication of how much meat there is in a dish (relative to tofu or vegetables) and prices that are widely divergent generally indicate different sizes of a similar dish.
This has worked fairly well for a number of restaurants so I decided to stop at a dumpling/noodle restaurant that I saw. It was a little more local (less western) in decor and lighting but the location was near some major hotels so didn't think it was too off the beaten path. I wasn't that hungry so I chose a plate of Bao Zi (dumplings) for 3 Yuan. In my mind, 3 Yuan should have bought me either 1 dumpling (if this were an expensive plate) or 3 dumplings. Imagine my surprise when they brought out a full steamer with 12 dumplings. I just kind of froze because I didn't want to insult them by eating only 2 or 3 and wasting the rest. After making sure that I wasn't paying 3 Yuan per dumpling on the plate, I proceeded to polish of 6 or 7 dumplings. I stuffed in the last two in me just so I could finish more than half the plate but it was hard moving around after that.
I think I had better actually learn to read menus correctly instead of coming up with complicated comparison formulas.