I had a Homelite straight shaft trimmer for over 10 years and it's still going strong, we just have to replace the string head every couple of years. I say "had" because my parents hijacked it and won't give it back now that the wife and I need it on our farm, lol. For a couple years, it was used pretty heavily while I was mowing yards to make some extra money during the summer.
Anyhow, I needed a weedeater the other day and attempted to use some cheap ass $60 walmart special that the in-laws had. It wouldn't even run without choking it to death for a few minutes, so I opted to go out and just buy a new one after that. I wanted to get something like a Husky but couldn't justify spending $250 on one, so I opted to go with a 27CC 2-stroke Troy-Bilt. I haven't had a chance to even take it out of the box yet, but hopefully it'll last as long as my old Homelite. Anyone had much luck out of the Troy-Bilts? I'm not expecting industrial grade from a $130 trimmer, but it'd be nice if it would at least last a few years.
I would think that since most trimmers and push mowers are pretty simple, you're really just buying a name since most of the engines come from the same source like the Briggs & Strattons that are in most push mowers. Granted some of them might make shitty decks that rust out in a couple years, but the little parts that might break are usually cheaply and easily replaced. You can get some genuine pieces of junk like a Weed Eater brand or something, but I think as long as you try to take half decent care of your stuff, you can make just about any decent made piece of equipment last quite a few years. Case in point, my old Homelite weedeater and Murray 22" 5HP push mower, both are still running strong after 10+ years of some pretty heavy use. All it takes is some routine maintenance, being stored correctly and not being abused by some half-wit.