Yes and no. Anytime you buy or do something, there is opportunity cost (opportunity cost refers to what you have to give up to buy what you want in terms of other goods or services..)
So if all you want is say arm load of GE product, you have to factor in the costs of lost wages or value of paid vacation, travel expense (gas, food, lodgings, park ticket cost, the value of any other activity you could be doing instead (even taking a nap has personal value to a person). You have to weigh those against the mark up of the item and dermine which is the better deal. So in this case, yes going eBay is better.
But if you are planning a vacation to Disney, or you live in Orlando and have season passes, these costs are much lower. You are already paying for most of the above already. You will get a better value personally buying the stuff yourself at the park.
So for each person it is different based on your situation.