You can purchase good cordless power tools online at Amazon.com, Buy.com or Ebay.com. It would be beneficial online, therefore you can compare prices, read reviews and return your product with no hassle.
Cordless power tools can be purchased at a variety of stores that would sell tools. Some stores that you may wish to try for the tools that you require are Home Depot, Lowes, Home Hardware, or Canadian Tire. You also have the option of purchasing the cordless tools online on sites such as ebay or Amazon.
There is no single best cordless power tool. Each manufacturer has good and 'not so good' tools.
I have many cordless tools ranging from 6 to 24 in voltage. I've found that most of the 12 - 14.4 volt tools are most efficient to use. Good power and good charge time. -More important is the battery make. Makita and DeWalt make the most efficient batteries. -I love many Ryobi tools, but some of their batteries, especially the ONE+ , are just terrible.
Cordless
I look at hundreds of tools and have never heard of them. -That is a clue.
I like this site for a good overview and starting point (it covers all electric knives, not just cordless): http://www.galttech.com/research/household-DIY-tools/best-electric-knife.php. There's also a couple of good reviews on http://www.cordless-electric-knife.com/.
Bosch Power Tools can be purchased online through the Bosh website www.boschtools.com. They offer a great selection of tools. Bosch power tools is also available through local hardware stores like Home Depot.
Some good brands of cordless can openers are Cuisenart and Oster. Those two brands specialize in kitchen products!
FEIN power tools are heavy industrial power tools. A general contractor might buy a Fein tool, which is great, but probably a little more than you need for hobbies.
The Panasonic DECT 6.0 Digital 5-Handset Cordless Phone is great.
There are several great places to search for good electric power tools. www.milwaukeetool.com sells Milwakee tools. www.toolbarn.com. Tool Barn also sells a variety of tools. Electric power tools and be found at local hardware shop and online.
It is good to have several basic hand and power tools when owning a new home. This will enable you to do minor fixes and repair on your own when needed.