I've joined a group that's going to be climbing Mt Whitney (elev 14,495') at the end of September, and when I checked my water filter that's been in storage for a while, I discovered it no longer works.
So, I did some research at the REI.com site to discover that the filter I want to get is the Katadyn Hiker PRO Water Microfilter. It retails at $69.95, but a quick search on Amazon showed I could pick it up for the low, low price of $58.30 (tax free and free shipping!). I quickly added it to my shopping cart on Amazon but then got distracted and didn't follow through on the purchase.
A couple days go by and I remember that tonight, I must purchase the filter, tonight! (truth be told: I won big at last night's poker game and so now I've got the cash to buy it)
I navigate to Amazon, click on the shopping cart icon and there's a note in big bold letters at the top of the page (not exact, but the gist): The price of your item has increased since you placed it in your shopping cart. The prices of items in your cart may change if you wait to purchase them.
The price of my lapse? The price on Amazon is now the same as any other place ($69.95), so there's only the tax-free, free shipping going for it.
Lesson learned. Don't make my same mistake.