How long it takes for an item to be repriced depends on a few different variables. Our system is designed to intelligently reprice ordered items more quickly than those that are not ordered as often. You will usually see changes happen within a few hours, but they can occasionally take longer.
Our default pricing formula yields a 10% profit after the eBay FVF and PayPal fees. Once you wait two hours you should see your new item prices in the eBay Listings Tab.
Here's a full overview of How Repricing Works.
Per-Item Margin Changes:
CHANGES SINCE PRICEYAK NEXT: In old PriceYak, if you wanted to change your margin on a per-item basis, your "Custom Variable" in Item Settings works as a percent, and .10 would mean 10% profit on that item, 1 would mean 100% profit.
In PriceYak next, you should just enter the percentage as-is. 10% means 10%.
Video Overview of Pricing Formula (a bit old, but good for how the calculations work)