I've got their daddies- the L630s- same speaker in size, driver arrangement, ect, but with cloth grill. And the L730s are also 6 ohm, compared to 8 ohm, and use Stifflite cones, where the earlier ADS L630s use Braun's original formula paper cones.
I love my L630s.
I'd value them, and your L730s at $75 to $150, possibly $200. Just great speakers.
In ADS's smaller "large" speakers, I'd argue the pecking order is as follows- ADS L810/L710, ADS L880/L780, and ADS L730/L630.
The L630/L730 models use a 1.5" tweeter, the rest use a 2" tweeter. I think the larger tweeter is a hair, just a hair, better. And although the L810/L710 bass is tighter than the rest, the bass in the others, while being a touch more loose, is still exceptional- and better to my ears than any other 10" woofer (even 12") out there, in my experiences so far.
You don't see many of the L730s out there, and even less of the L630s, and there's a reason- they are exceptional.
Same for the L880s, except I have read through research that the woofer in the L880s and L780s are a bit tempermental at times. Cannot verify this as fact, only strong suggestion.
There's a rare bird out there, the Braun 830 (no "L"). I'd love to see one at some point, in person. My friend Bolly, a former member here, has some. If I recall correctly, it's pretty much a L730 with a 2" mid like the L880- or an L880 but with the earlier L730 woofer.
Anyhoo, enjoy those my friend. And if you would be so kind, please throw up a picture of them- I may refinish my L570 IIs this spring, and am considering going to a bronze grill.
Best,
Paul