Two terms first, since they're the ones the pricing hangs on.
Stacking criteria means filtering a property database by several signals at once. Instead of "all houses in this zip," you ask for absentee owners, meaning the tax bill goes to a different address than the property, with high equity, meaning the estimated value is well above the loan balance, and long tenure, meaning they've owned it many years. Each filter you add shrinks the list and raises the odds the owner would actually consider selling.
Skip tracing means taking an owner's name and address and looking up phone numbers and emails for them. It's a separate data purchase from the property record.
On cost, the common shape is a monthly subscription in the low hundreds that includes a set number of record exports, with skip tracing either bundled at a low per-record rate or billed separately at a few cents to a couple of dollars per hit depending on volume and how much contact detail you want. Cheaper tiers usually mean fewer exports, thinner court-sourced data like probate and pre-foreclosure, and no team seats. Prices move around, so get the current per-record and export limits from the vendor in writing before you commit.
On licensing, buying property for your own account isn't brokerage. You act for yourself. Licensing questions start when you're getting paid to market someone else's property, and where the line sits varies by state, with some states having specifically addressed wholesaling. Ask a local attorney about your state before you build a process around the answer.
The cost people forget is phone infrastructure and the labor to actually dial, which usually exceeds the data bill.
