@pwn3d
I link my A1200 through the net with the real 3COM 3c589C PCMCIA card. I bought both of mine for less than $5 USD each and the only real limitation is they are 10-Base-T only, but they work fine. Software wise, just use 3c589.device and either Miami, AmiTCP 3.3, and/or programs like EasyNET (which is obtained through Amigakit and normally bundled with the NIC s they sell).
The Blizzard 1230 Mark IV (which I just sold mine) allowed for RAM expansion up to I believe 256M using older 32 PIN PC memory. These accelerators fetch around $100 USD.
I agree the prices are way outrageous on this hardware, but people obviously pay it or they would drop.
I agree with everyone that said demand way outweighs supply as the reason for this.
What can you say, Amigans are stubborn people when it comes to our platform :-)
However, the good news is, it is quite possible to do day to day work on your Amiga computer if you expand it out.