By Ashley Watson, dealnews writer Pop Tarts for 18 cents each? Raisin Bran for $1.74 a box? Some of the prices we list on dealnews for offers from Amazon's Subscribe and Save program sound incredible. Too incredible? While others have tested out the program to see how it fares, including the New York Times, we needed to see for ourselves how it really stacks up, over time, and if the prices hold up over many months. The program, which offers free shipping and an additional 15% off of all eligible items, works like this: You sign up, select an item, choose when you want it shipped (in intervals of 1, 2, 3 or 6 months), and voila — you've just made the cheapest, easiest purchase on an item you regularly buy. We started at the top, with our own dealnews CEO, Dan de Grandpre, who reports that the soap he orders on a regular schedule via Subscribe and Save has held a consistent price over several years. In fact, his last order in March 2011 was actually 77 cents less expensive than his first order four year prior. So his costs have actually gone down very slightly over time. Liz Dialto, a health and fitness expert, uses the program to save on protein bars and powders for clients. Dialto says that she saves around $8 per box on her monthly purchase of protein bars that she would normally buy in a store. As a city dweller, Dialto says, "This is also superconvenient for me as someone who tries to keep my grocery trips as efficient as possible and doesn't want to carry 100 pounds of groceries." Overall, she says, "I definitely think I'm saving money and don't see any drawbacks." But even if Amazon's prices can beat a regular store, what about other online discounters? We compared the prices of some of the same items our focus group buy at Amazon with the deals at Soap.com. While Soap.com is actually owned by Amazon, which bought its parent company in 2010, they operate as competitors. Here's what we found in an online search (keep in mind that the savings total includes the shipping cost at Soap.com, since they only offer free shipping for purchases of $39 and up), prices valid as of March 7: Item Soap.com Subscribe and Save Savings Aveeno Ultra-Calming Daily Moisturizer SPF 30, 2.5-oz $15.19 $12.74 $7.44 Clif Bar Builder's Bar, Peanut Butter, 2.4-oz bars, 12-pack $19.99 $15.21 $9.77 Source Naturals Vitamin D-3 1,000 IU, 200 tablets $5.74 $4.49 $6.24 Not only are the actual prices cheaper through the Subscribe and Save program, but Soap.com charges a $4.99 shipping fee for purchases under $25, and $2.99 for purchases of $25 to $39. The only catch we could find is that the Vitamin D supplement only comes in a 3-pack on Amazon (for $13.36, which works out to around $4.49 a bottle). Unless your entire family is taking it, buying in bulk may not make sense for an item that could expire before you use all of it. Still, Amazon's prices were consistently cheaper, even with some of the coupons offered at Soap.com. But just in case, we got a few more responses from the most trusted super-saving shoppers of them all — the moms. Ali Gerakaris, a marketing manager, tells us that the program saves her money and time. She comments, "As a new mom with a full-time job, I never have to worry about whether or not we need diapers. They just magically appear at my front desk!" During our research, we also noticed that Diapers.com (a sister company to Soap.com, also with Amazon as a parent company) offers a coupon for 30% off of three months of diapers and 10% off everything else. Even though these were restricted to new customers and certain brands, we wanted to compare prices for diapers and a few more of those items that parents reach for so often. Here's what we found (with the same shipping fee disclaimer as before): Item Diapers.com and Soap.com Subscribe and Save Savings Huggies Snug & Dry Diapers, Size 4, (126 ct and 140 ct) $37.99 $28.55 $12.43 Tide Original with ActiLift, 64-load $15.30 $14.44 $3.56 Charmin Ultra Strong Mega Roll, pack of 6 $9.25 $6.78 $4.54 After price-checking, we realized that the Huggies brand was not included in the 30% off coupon at Diapers.com, but even with the 10% discount for all other items, it's still cheaper at Amazon because of the $2.99 shipping fee at Diapers.com (where you have to spend at least $49, not just $39, to earn free shipping). The same goes for the laundry detergent and toilet paper; the cost of shipping is the same as the amount you would save on a 15% off coupon, which is for new customers only. Also, if you are a member of Amazon Mom (or want to join for free), you get an additional 15% off, bringing your total on Huggies down to $23.51 for a 140-count package. In sum, Amazon Mom members save $13.67 on Huggies diapers by using Subscribe and Save, and they get 14 more diapers per package — that's $0.17 per diaper compared to the unit price of $0.30 at Diapers.com. Whether or not you have kids, there are at least a few items you always run out of, and who wants to run back out to the store? From what we can tell here at dealnews, you probably won't find an easier, more cost-effective way than Amazon's Subscribe and Save to ensure that you never run out of those items. Nor will you find a better deal on the items you may never need again. All you need to do is cancel after you get your order. Ashley Watson received her MFA from Goddard College in January 2006. Upon completing her degree, she taught writing composition at the University of Arizona and began her career as a freelance writer. She is a contributor to the 2007 Teacher's Guide to Living Literature: An Introduction to Fiction, Poetry and Drama, and she has published articles in various online and print magazines. She currently resides in Vermont.