Always on Sale
Don't be too overawed by steep markdowns on treadmills; it's common practice for most brands to price their machines ridiculously high, then offer near-perpetual "limited time only" discounts of anywhere from 20 to 50 percent.
The Best Bargains
Dazzling sales aside, the best deals on treadmills are usually available early in the New Year. Some sporting goods stores may advertise treadmill deals on Black Friday or the day after Christmas too, but don't get so taken in by the bargains that you buy a model you don't really want.
Much like buying a car, you can also get excellent deals if you wait until new models are released and then buy the previous year's model. When those new models are released varies by manufacturer, and not all manufacturers update their equipment every single year.