NavList:

Basically, the value is whatever you are crazy enough to pay for it as actual prices are all over the place. I've seen them go as low as $600 and as high as $4k+. I've used the dragonfly, and have both of the newer iterations of the Plath AH, as well as a C&P, aTamaya Continuho-style AH and a repurposed A10 bubble sextant AH.

thus my take:

C&P AH: If not too expensive, my first choice for actual use. Can find retail price at multiple locations online. Look for new old stock. Anything below $1k is prob an acceptable deal.

Plath Dragonfly: first choice if you are a persnickity collector and want the brand of your AH to match your sextant. But note that it has been so long since they were manufactured, chances are that even one in "working condition" is going to need adjustment. Noting that you will be competing against both practitioners and crazy collectors, you will be lucky to get one in clean working condition for less than the cost of a C&P AH.
The Dragonfly's main feature is that it has an adjustable bubble, but I find that the well-designed reticle on the C&P AH obviates the need for the adjustment. And a converted A10 bubble AH will also give you adjustabiity at a much lower price.

Newer Plath AH's: latest model (with LED illumination) isn't of interest other than as a collectible. Model bet it and the Dragonfly is a fine AH with adjustable illumination (no bubble adjustment), but I still prefer the C&P AH.

Converted A10 bubble horizon: Is really solid for actual use, no collector value. Reasonably priced when they turn up (think well under $500), but don't turn up that often. But very easy to adjust, repair, etc. Perfect for folks who are hands-on types. Bill Morris has some very helpful guidelines on his site along with all his other extremely helpful info.

Sextants/AHs in general: Friends who are antique dealers tell me that the prices for sextants and accessories is down substantially from a few years ago. so don't let bubble fever get tempt you into paying too much.

continuho-style (Plath/Tamaya) AH: pure collector's item. Impossible to actually use -- like patting ones stomach while rubbing one's head while balancing on a beachball and swatting off wasps. Those zeppelin pilots must have been gods to make the crazy thing work...

Overall: As been noted on this list many times, Bubble horizons are useless in actual practice on a small boat. Work fine on land, but a mirror horizon (properly adjusted, etc) will give a better result. But if you have a weakness for fine machining and a love of pointless complexity, bubble AHs are the way to go!
-p
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