Sounds very similar to a situation I've looked at. Does the manufacturer have MAP pricing enforced? Often this is why most people can't compete on ebay, because they don't do a good job enforcing MAP pricing.
Assuming that's irrelevant for your situation, people may be selling refurbished products.(this was the case in a product we are selling) Therefore, there's no guarantee on the product through the manufacturer, and some people are okay with that and willing to pay a bit less to get the product this way.
If you're just buying an already established product/brand out of season, just make sure you know the pricing when it's in season, and if you'll be able to sell it at the same price when it's in season again.(make sure there's no new model coming out, etc...)
ebay/amazon are fine for tests, but in both those channels you're competing on price. If you're buying discounted out of season stuff, that's really all you're going to be competing on anyways since it's not a unique product from anything else.
Since it sounds like you need to sell them asap, but you're saying you can't compete on price, I'm not sure what you're looking for- unless you're looking to sell them to local businesses who might only need a couple, but that seems like more hassle than it's worth.