I agree audiodrome & Chonny!
The whole premise of "collectibles" as an investment is nothing more than a paper tiger. Whether it's musical instruments, baseball cards, beanie babies (remember the stupid prices on some of those?) or stamps & coins, the very idea that the average person can fund their retirement by "investing" in collectible items is ludicrous. The uneducated sellers who overprice a "rare" or "collectible" instrument either out of greed or ignorance will find themselves left holding the bag, as many cash-strapped potential buyers will be bargain-hunting.
True, there are certain items that will always command a premium price in the collectible market due to the perceived value determined by the relationship between demand, condition and rarity, but the only people who have the spare coin to purchase such items are the same people who can afford to take a loss on them.
I think a large part of the current vintage & collectible guitar market is primarily driven by baby boomer nostalgia, and the flawed perception that "old" = "valuable".
I buy vintage instruments from time to time, but only if they are within my disposable income budget, and ONLY if I can make use of them... e.g. are they playable, in decent (not necessarily pristine) condition, and if I actually LIKE the particular instrument. These are not the only parameters by which I decide to buy a vintage guitar, but I can tell you that perceived "collectible" value never even enters the equation. I buy a guitar because I like it, not because I expect to make a mint off of it in the future. If it goes up in value, great. If not, big deal. That's why playability is key for me.
I'm always looking for bargains, and I've been socking away extra cash for a few months now, waiting for a downturn in the market. Hopefully KCeddieB is right, and we'll begin to see all the suckers clear out of the market at reduced prices.
Bottom line is that the true value of something is determined by what someone is willing to pay for it. And most folks are a little more judicious with their pocketbook in an economic downturn. This means that they will be less likely to pay $5000 for a 60's Strat when there are thousands of them available.