Unfortunately, group buy is not an option as they have been long out of production.
Out of production....yeah, that's a problem with getting a group buy.....
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Just be patient and something will pop up on eBay for a reasonable price. With respect to the crapshoot, based on my experience the odds are in your favor. I have purchased many and approximately 80% are the newer 3 ohm version.
I concur with George. Of the different flavors that I have purchased on eBay, both the straight slots and wavey 13 slots, most of them have been the 3 ohm (actual measured value is around 2.8 ohms) version.
Ed