As the fourth generation of Nordstrom Inc.'s founding family spent the summer exploring the idea of taking the retailer private and scouting for financing, one thing was clear: It wouldn't come cheap.

The family needed roughly $7 billion to fund the deal, and lenders demanded a steep interest rate, according to people with knowledge of the matter. After meeting at least nine different firms over the course of four months, the asking price came to about 13%, said the people, who requested not to be identified because the discussions were private.

That's roughly twice the average borrowing cost for typical retailers, and it's a rate that few otherwise-viable businesses would be able to sustain.