I've bought from them numerous times, even rugs and small pieces of furniture--no problems. (Looking in my Overstock account, I see 5 items bought from them this year alone, including an inversion table.)
You can use one of retailmenot's codes:
Overstock Coupon Codes: Coupons, Promo Codes, Free Shipping for Overstock.com
If you are a new customer, the 12% off link might work. Otherwise, the FREE SHIPPING ON ELECTRONICS is sure to work.
Docrwm, thanks for the link! I've ordered one. I had/sold a few copies of the kit lens, but keep coming back to it. It's light and very sharp in the 20-40mm range. With the WR, it's even nicer.