Do not buy your gas powered things at Home Depot or Lowes if you want one that is more likely to last.
Buy Stihl or Echo, in that order, and buy them from a dealer. There's no reason to buy Echo from Home Depot...the prices are the same, the products are the same, and even if it's on sale, the dealer will match, and he's the guy you're going to take whatever you buy for service.
Eh, they won't always match prices. And the dealers will service products they didn't sell with no objections at all. It's not like the dealer is suddenly going to remember a homeowner from five years ago either.
The only worry is that manufacturers might have different part numbers at HD or Lowes (not the case for Echo) or limited selection at HD/Lowes.
For example, it's incredibly rare to find any Echo trimmer above the SRM-230 in a store. They can order one for you, but I've yet to see an SRM-266 or SRM-280 model in an actual HD/Lowes store. And the people there can't really tell you what the benefits of different models are (e.g. steel driveshaft has more vibration, but is more efficient at power transfer and works better with blades and other brush-cutting attachments).
I prefer dealers since they're generally much more knowledgeable about the products, but that wouldn't stop me from going to Lowes or HD if it meant saving a bunch on something that was exactly the same as the dealer had.
ZV