For me, I don't tend to care much for the brand name unless it is something I have never heard of before or a type of product where there is a significant variation, such as computer power supplies. The most important thing is that it has the features I'm after. Even then, I would still check online user reviews (such as on Amazon, NewEgg, etc.) to see what others think of the product. I also tend to avoid getting a product that has just launched, as I've been caught out before.
Once I decide on a product, what's really important for me is where to get it than simply looking for the cheapest price, unless there is a drastic (e.g. >10%) price difference.
I would rather pay a little more to buy from a shop with a reliable after-sales service than another shop that has it cheaper. For example, I never had any issue returning products with Dabs despite several products I've returned over the past few years, however, I've had a real pain with Komplett trying to get a Panasonic projector RMA'd where they insisted I had to go through Panasonic and the Panasonic insisted that it's Komplett's responsibility. Eventually I had to go through the national consumer affairs agency to get this sorted. So as you can imagine, I've pretty much stopped shopping at Komplett even if they have the product cheaper.
For small items, such as power strips, batteries, USB cables, ink cartridges, etc. which would not be worth RMAing if they fail, I tend to go for the cheapest shop, since some shops put a very hefty premium on such products.