As a repair tech, the problem I've found with the cheaper Brother sergers is that they can't hold a timing setting because the metal is not the best quality. They use a softer metal. So when the timing goes out, your repair tech may be able to re-set it, but it won't stay set.
Juki makes a really great serger for a great price, with quality parts. I always recommend a Juki over a cheap Brother or Singer serger.