...do great speakers increase in value over time in the vintage market?

Hello to all...

I have a pair of JBL L25 "PRIMA" speakers, made 1972, case in 7/10 shape (not repainted), surrounds on woofers reformed several years ago, grill cloth replaced several years ago, includes JBL badges on speakers. Original 1972 price $169/ea. 

Recent searches of this speaker in the vintage market show prices 50% OR MORE than the origional issue price: ???

Is this that good a speaker design? - I have read comments saying it his/was one of the best speakers ever made by JBL (at that time?) - and I do luv their sound (which I now wonder if I've ever really heard them?) especially with well-recorded jazz and have the ability with little power to ROCK OUT!

(Would greatly appreciate any comments by those who have/had these over the years...)

DO GREAT SPEAKERS INCREASE IN VALUE OVER TIME, or do/should all depreciate in value...
Goodmans did sell speakers in finished cabinets in the UK in the 50s.  My father had a single one (mono) he must have bought then.  He moved to stereo soon after so when I built my first stereo system in 1962 I purloined it and 'matched' it with a Wharfedale he also had in store that was taller and thinner with a darker cabinet.  Both two-way, the Goodmans sounded a lot better.  You could almost see the sides of the Wharfedale cabinet flapping.
I just restored a pair of AR 10 PI speakers ,new foam surrounds ,all new caps and resistors, new grills ,refinished cabinets,got the speakers cheap $200.00 ,total cost was $500.00, These sound great!!! I have a pair of Focal 1028 Be ,I used a pair of Rel 3Ti subs with both pairs ,both sound great but ,different, The ARs weigh 56lbs each .built very well, In 1977 they cost $900.00 for the pair today cost would be $3973.00,Not bad for $500.00
I agree with chrshanl37. When inflation is factored in, there is generally no appreciation. I had a pair of JBL L-166 that I had to sell during a divorce (still sad about that). They generally retailed for about $800 a pair in 1979/80. I bought mine at an employee discount of $500 a pair. When factoring in inflation, the $500 is worth about $1700 today. If they were purchased at the 1979 $800 retail price, it would be about $2500.The last time I saw a well restored pair of these for sale, they were listed at about $1000. The new JBL 4319, a close approximation of the L-166's, sell for $2500 a pair. I believe they are manufactured in Japan and look to have a similar build quality as the classic "L" series of the late 70's.
I've done my time (like brief prison sentences) with various vintage gear. I would never turn to vintage to get superior sound, and in my estimated 99% of the cases are lousy "investments ".
Vintage is good for nostalgia. Buy at your own significant risk of poorer sound and loss of money.
The vintage market is driven by nostalgia. People lust after something when they can’t afford it and then come across it when they can. My first good speakers were LS3/5as, bought for $650 in 1981. I somewhat regret selling them to get my first big electrostatics a couple years later.
the problem is that they are functional items which suffer with age (capacitors, surrounds especially). The market is also driven by ignorance. A new pair is &3k and are bested in every way by a pair of Paradigm 15Bs for half the price.
wilson Audio speakers are remarkable for holding value after initial depreciation. They are far better than other speakers, but I still would rather have a smaller new Wilson than ones even one generation back, as the best designers keep learning!