Quite a few guitar companies have done a great job of maintaining their brand name and product quality/value despite a poor economy. What factor drives the value of musical instruments?
High quality instruments, when maintained properly, keep their value better than nearly anything else. Other than a loss of value immediately when it is purchased and becomes "used", a used instrument can be kept remarkably well if cared for properly. While novelty value is quickly lost, such as vintage replicas and all sorts of limited edition junk that big name companies put out, high quality builds that are playable and sound good keep a lot of value. While the Gibson Les Paul Standard runs around ~$2500, they normally resell with years of play for ~3/4 of that if they are not abused. The Alex Lifeson signature Les Paul Standard sells for ~$4000 new, and loses most of the $1500 difference immediately if you resell it as used. I got a good deal on a discontinued ESP LTD guitar and almost two years later it holds nearly the full value of what I paid for it.
What other hobby/pastime holds value like this? Cars lose value simply by becoming a year older, while guitars have only the initial loss of value, but value mostly due to damage and abuse after that. "Vintage" stuff is an exception to some extent - it can sometimes gain value, but the majority of things simply lose value with age unless they have quality that holds up over the years.