Do two things. I promise, even with the added steps, it'll be much faster than a Walmart checkout line.
First, run a search on the product name, especially if you're not sure what the normal price is, or the item's apparently being offered at some incredible discount, like on daily-deal sites.
For example check this out. It's a foot rocker from a daily-deal site! It's 75% off! Shipping is only $2! You can fix your plantar fasciitis AND save big bucks! I think the excitement of it all might kill me!
So I pop this into Google, and get the Amazon result:
It's the same foot rocker! It's got a bunch of reviews, so I can decide if it's a product I want, or if something else might work better! It's the same price per item, and I think that trying to use two of these at once might be dangerous, so I can handle that! Shipping over $25 is free, so I can get this, and some books to read while using it! It's even more exciting!
Of course, after reading the reviews, I'll want to do a little more searching, to see if there are better prices elsewhere. I'll also want to do a quick search on retailmenot.com, to see if there are any coupon codes. I might also want to see if a cash-back site like ebates.com or shopathome.com offers anything for the store I choose. I think that might have just become three sites. Whatever. Still faster than Walmart.