What he said, basically.
The 68060 is a dodgy deal at the best of times. Jens has worked very hard to build up a reputation of quality hardware, it just doesn't make sense that he'd risk a lot of time and money in developing a board when the only supply of processors he has is from Chinese resellers who are apparently selling chips which the manufacturer denies all knowledge of. I know I wouldn't do that in a million years.
And what is the gain of making a 68060 accelerator anyway? It's not necessary for 95% of Amiga stuff, and for the other 5% die-hard Amigans can still get 68060 accelerators on eBay or whatever - sure they're more expensive, but a lot less expensive than developing a new accelerator. Like it or not, most Amigans use 68030 because it's probably the best compromise of compatibility and speed, and often use WinUAE for stuff that depends high power. There's not really a great many people out there who would cough up the extra for a 68060, as most people just don't have the need.
I keep seeing people posting about how "x should do y" all the time. Building an accelerator isn't just a matter of soldering a processor onto a board, shoving on a few RAM chips, and packaging it in a nice glossy box. It takes a LOT of time and effort to design new hardware like accelerators, jamming a processor into a machine that was never designed for it. The more different the CPU, the more work (and therefore cost) it is - and the 68060 is very different to the 68020/30.
@donpalmera
Welcome to Amiga.org - nice to see such a useful and pragmatic poster!
@Iggy
Quite right. eBay isn't the seller, it's the person who's doing the selling who's the seller. If people only bought from reputable sellers like you or I, they wouldn't have the same problems.... but I keep seeing eBay getting the blame because they bought something cheap off a shady bloke with no feedback.
Caveat Emptor, and you'll be just fine on eBay.