Believe it or not, the start of the holiday shopping season is already upon us. (Yes, it’s only November 11.) 

Stores and online retailers are trying to suck you in with emails, discounts, Black Friday promotions. But how much of a bargain are you really getting?

Mark Ellwood is the author of “Bargain Fever: How to Shop in a Discounted World.” He spoke to Marketplace’s Lizzie O’Leary about discount shopping and the holiday season.

From Amazon:

Paying full price is so passé. A quarter of the population will only open their wallets if something is on sale. Everyone wants a deal, a steal, a hookup with a discount or a way to cut costs. People don’t only want a deep discount, they expect it and won’t settle for anything less.

They’re lucky, then, that almost half of everything sold in America is listed at some kind of promotional price. It’s a seismic shift that has made shoppers more savvy than ever, generating phenomena like extreme couponing, flash sales, and Groupon. 

So there’s never been a better time to be a buyer, right? Perhaps. Sellers have developed their own tricks to protect profit margins amid such markdown mania—ones that include secret sales, shifting prices, and shredding perfectly good clothes.

In this playful, deeply researched book, journalist Mark Ellwood takes a trip into this new landscape. He shows how some people are, quite literally, born to be bargain junkies thanks to a quirk of their DNA, and uncovers the sales-driven sleights of hand that sellers employ to hoodwink unsuspecting buyers.