Amazon has quietly entered a new market with the launch of Amazon Prints, a photo printing service that already has one key competitor reeling.

The new service, which went live last week but is only now being reported on, allows Prime Photos and Amazon Drive customers to print individual photos and photo books with prices starting at $0.09 and $19.99, respectively. The landing page notes that custom stationary and calendars will soon be offered as well.

At $0.09 per 4x6” print, Amazon is undercutting market favorite Shutterfly by $0.06. A 5x7” print, meanwhile, will cost you $0.99 on Shutterfly but only $0.58 through Amazon while an 8x10” print will be $2.20 cheaper with Amazon. A savings of six cents here or there isn’t much but it can quickly add up to significant savings if you’re ordering a lot of prints (assuming of course that you’re already a Prime member).

One unknown at this time is quality – how will Amazon’s prints compare to what Shutterfly offers?

Victor Anthony, an analyst at Axiom Capital Management, told Bloomberg that Amazon’s new service couldn’t have come at a worse time for Shutterfly, a company that earns nearly half of its annual revenue from customers printing cards and calendars for the holidays.

The launch was felt in the stock market as well as Shutterfly experienced its worst single-day decline in more than eight years on the news.