I don't know how far these dudes have got with this buthttp://usbip.sourceforge.net/
USB over tcp/ip.
If that software actually works then the issues become;
A) finding a decent network card for an amiga. (I don't know if that's an issue / how much of an issue.)
B) Getting that software ported to Amigoid OSes. ( Power2People bounties
Then you could run Aros (Or Linux or whatever else) on some POS old PC and serve it's USB over your LAN to your actual amiga.
How's that for a sweet theory, the practice might be rather different.
On the topic of heinously expensive hardwarehttp://rhombus-tech.net/allwinner_a10/
I mentioned this on Aros-Exec in the hope that it would spur some ARM love, it's like the Raspberry Pi but potentially cheaper, potentially more open (see ARM Mali driver reverse engineering being done elsewhere) and much more powerful.
It's an interesting psychological exercise to read that page and keep reminding yourself of the features and price of an X1000.
edit: Sorry I didn't notice that you were also bitching about the cost of network cards. I guess that USB over TCP/IP brainwave doesn't even work in theory then. Hmm.
What about something like this then?http://www.saelig.com/product/ETH026.htm
It's a network-stack-on-a-chip with RJ45 ethernet on one side and a serial port on the other.
Sod it, we (Team Crap) can buy a heap of them in, Franko can do the Youtube promo videos and box art, I'll pink lint all the amiga forums hawking these things, we can all chip in for a http://www.reprapcentral.com/vmchk.html
to print little cases for them and sell them on amikit for $200 a go. Woohoo, we're quids in!
Back to reality: I assume that would work for you. (the WIZ110SR Serial to Ethernet Module, not the business plan)
Edit: Wait a minute, You'd still need the usb over tcp/ip software and you'd need a new upgraded serial port eh?
What about those PCMCIA to USB adapters that you used to get for ancient laptops. Don't they work with A1200 / A600 at least? Or is there no software?
Bollocks to it, I give up, just wait for a Natami or an FPGA Arcade. Lol.