Hi, love the setup you've got there!
I especially like the cut-'n-shut Amiga keyboard, though I'd be terrified of doing something like that to one of mine.
Yes I do think the A4K desktop setup is a good way to go; there's lots of fun putting it together and plenty you can do with it after.

I have the CV64/3D w) SD but the SD has caused me a lot of problems. (I cut my hand badly putting it in and now I can't get it out!)
I do like the card though and not sure what the advantages are of having a Picasso 4 instead?
I personally don't think it's crazy spending money on this old hardware. If for no other reason they're collectors items and that would be good enough for most 'sane' people. But plenty of people spend lots of cash on designer clothes and things they don't need and I'm not interested in any of that, I would much prefer a nice clean Amiga 3000/4000 instead! :-D