I can see that a price difference would be a problem but are you sure there isn't a difference in after sales service?
Good customer service is worth paying a premium for in my opinion so, for anything that's a significant investment I will buy items from companies that have a good reputation rather than the cheapest, even if it's exactly the same product with a different name on.
On the other hand, if it was something that could be regarded as throw away on failure (I very rarely do that) I don't mind shopping for the cheapest possible.