As a rule MEC doesn't carry junk, so their cheapest option for product x (say, headlamps) will be higher than almost anywhere else. That said, over the years I feel as though I've noticed an increase in pricing on specific items as compared to other retailers. In the past MEC usually undercut other retailers on same Brand/Model items (co-op buying power). But since internet retailing has exploded in the last decade or so, reputable brands have had to come up with ways to protect their dealers (specifically brick and mortar). Many companies have instituted Minimum Pricing rules, which prohibit a retailer from selling a product below a certain price. This protects all retailers from a race-to-the-bottom WRT pricing, and assures everyone a "fair" margin for retailing the product. I expect most of the brands that MEC carries have some form of a minimum pricing policy. These days it seems that MEC's pricing is generally equal to other retailers. I used to work in the bicycle industry and this was a huge issue as online retailers gained traction.
On top of that, in my opinion MEC's house brand used to be less expensive than an equivalent independent brand's product, while offering about the same quality in many cases. Or at least sufficient for the price. These days I feel that their house brand usually costs at least the same as the other established brands, while not offering nearly the same quality or workmanship as in the past. That has been a disappointing change. But otherwise if you have a specific product in mind, I still haven't come across many cases where MEC isn't the cheapest, or equal in pricing, while offering excellent shipping rates and the best (to a fault) return policy.