Four things decide the price. Whether the lead is exclusive or shared. What was checked before delivery, because a phone verified, finance screened record costs more to produce than a form fill. The states and loan purposes you want. And the volume you start at.
The number to compare it against is your own. Work out what a settled loan is worth to you and what share of leads you close, and the price per lead either fits under that or it does not. There is no retainer and no lock in, so the test is short. The steps are on the page about how to buy mortgage leads.