I'd love to post my turnip prices daily in AC:NL. I can let you know how much they're going for. I'm trying to turn some profits, and would love to help you do the same.
EDIT: This may actually not be such a great idea since you'd have to do quite a bit of traveling if you have many turnips.
In wild world i play the stock market a little bit(only 400 turnips in 3 towns and 500 in another) but since it contains the turnip table glitch and at least 1,000,000 in each town, i don't do series tracking on a regular basis.
In ACNL, the current plan(unless something changes) is to do it enough to get my turnip badges(B, S, and G levels) then i'll probably only rarely do it. Without the security of the turnip table glitch and no current plans of doing regular wifing, I doubt i'd do it much. It's going to take a nice amount of coinage to pay of the mortages(i'm doing 3 houses in the game and mom called claim on #4), decorate 3 houses, set up clothing for the characters, do the projects i'm planning on doing(the mall district stuff, cafe, and bridges), and filling up my catalog(partially the buying stuff to do the above things and partially getting stuff to send to neighbors/help out with hobbies). I know that the prices could equal a pretty good profit but i don't always have time to track prices closely during the week and could just wind up not making much, if anything at all.