You're probably aware of this, but just in case...the NCAA ran a women's NIT for several years but finally dropped it a few years back. Fans showed little interest, and few seemed to care when it was dropped. Now, with a surge in interest in women's basketball, they've brought it back as the Women's Basketball Invitational Tournament.
In the absence of an NCAA invitational, a private organization started putting on a tournament under the name WNIT. That tournament also still exists but is now third-tier behind the NCAA tourney and the net WBIT. That tournament has some pay-for-play elements. Teams are pretty much on their own when it comes to costs.
You are taking a "long" view, I must say. Triple Crown Sports started the current version of the WNIT in 1998, the NCAA had dropped the postseason women's version of the NIT in 1996.
The WNIT is "pay for play" in the sense that you pay pretty much your own expenses and you pay (and bid) for the privilege of hosting. Some schools have a history of (fairly) decent attendance and a few years back Arizona bid high and grew the crowd every round through the finals, which drew over 14000 fans and was effectively sold out. But most schools don't really draw much to games so the early round losers I suspect lose money as well as games.
The new WBIT that the NCAA is running has some of the traditional NCAA benefits financially, although I have no idea exactly. Plus, the "final four" of the WBIT will be on a neutral court.
Incidentally, if you want to go back far enough, the transition from the AIAW to NCAA was partly driven by the NCAA financial benefits - in a recent program, Vivian Stringer spoke about the reason Cheney moved to the NCAA from the AIAW, relating to the cost sharing benefits that the AIAW didn't offer.
