@AmigaClassicRule
Please don't buy an ACA because you expect a faster one later - I think it's very unlikely Jens will make one, and he's never promised he will.
Things to bear in mind:
The 68030 is based on the 68020 - it's a simple accelerator. The 68040 is NOT - it is quite different, which is why you need 68040.library and not a 68030.library. 68060 is closer to 68020 in many ways, but in other ways even more incompatible.
The 68040 is a real heat monster. This is why you should only use 68040s in towered Amigas. 68060s are better.
68060s are near impossible to find new, I believe. Chinese suppliers claim to have them but there's doubt as to how genuine they are. 68040s the same, but I don't even think the Chinese sell them.
I can't speak for Jens, but I get the strong impression that there will be never be a faster ACA than the 56MHz one - and he's already discontinued that one.
Certainly don't just buy an ACA in the expectation of getting a faster one down the line - the ACA is a fantastic accelerator as it is, buy it for that reason. Then you won't be disappointed.
Incidentally, a 200MHz 68030? Maximum speed on a 68030 is 50MHz (the 56MHz is overclocked and pushing it) I believe? 200MHz or even 100MHz is completely impossible without a major redesign - and it wouldn't be a 68030 any more.