Blame UPS for the shipping and Amazon is the online equivalent of Walmart - they'll take a loss on some products to be able to undercut all other vendors.
I manage an eCatalog for a family owned local hardware store, and both UPS and Amazon are the bane of my existence. UPS borders on complete randomness with what they charge to ship and how long they'll take to do it. Amazon borders on violating MAP (minimum advertised price), anything
not limited by MAP and costs less than a hundred bucks ya might as well not even bother to sell as the profit margin is so narrow, usually about 7% = $3.50 "profit" for a $50 product to compete. This hardly even covers packaging let alone any other overhead... like customer service.
As the retailer searches for ways to restore profitability, sales competence and expert servicing of product are the first things to get cut out of the offering in an effort to retain a reasonable return on investment on a low price sale. This leads to improper sales advice to consumers, inadequate service and poor adjustment of complex products. All of this lowers the satisfaction of the end consumer with the product. Ultimately, if the dealer sees the market price as too low to sustain in a reasonable manner, the product will simply be dropped from his offering altogether and the product becomes difficult to find. Low price, initially a positive for the consumer, can become so low that the consumer ends up not getting what he bargained for.
So with a one time purchase of a cheap plastic part, you may wish to save a few dollars and buy from Amazon - know that the situation is far more complex than what appears to be just profit hunger. As a private business, we go really out of our way to ensure customer satisfaction with extensive support and friendly, knowledgeable staff (whom even speak english OMG), repair/replacement of even un-warrantied items is not uncommon. The more the Amazon/Walmarts dominate the market - the less the smaller, more customer-focused business can compete and will stop even offering the smaller items for online sales.
*shrug* So it's up to you whom you wish to support. I would recommend
not making any online purchases that costs less than say fifty dollars or so as simple S&H will negate any savings found online - for something like the MixMizer I would have waited till I could add it in with other items purchased from a retailer that actually cares and stands behind their products - or just getting it from a local hardware store (which may be the same thing lol).
In any case, a business has no control over what UPS charges... or even a clear idea what they may charge as it fluctuates constantly. Using your MixMizer example - if the part costs $6 and S&H to Canada costs $12, do you
really expect a small business to take a $6 loss per item sold just so you can get free S&H? Note this
isn't $6 less profit - it's
spending $6 to
give your product away.
There's a LOT more to your money than just getting a shiny plastic thing, just as there's a lot more to "saving" a few dollars than just buying the cheapest thing you can find. Amazon depends on consumer ignorance - be smart and think what you're supporting before you buy.
/end rant
