I've got an idea, that we could have updating supermarket prices on the lolnet forums as an active post all the time so even though we are not online, we can still see how the market is treading.
Feedback would be appreciated about this.
Atm, Supermarket prices don't fluctuate in any direction except to better evaluate it's worth. Doing this manually is quite difficult and time consuming for little reward. However I believe there are some plugins being discussed that can provide dynamic market prices.