yes, you can indeed save a lot of cash with some DIY if you consider the 'raw' material costs - but time and making of printed circuit boards can't be neglected...
In that sense you might start with tube technology using point to point wiring - avoid high voltage layouts for the beginning, tho
Before thinking DIY multichannel converters take a comfortable seat - you cannot even beat Behringer and there's at least one product (with less features) for about half that price (dunno it's quality) afaik.
An Adat with worn out drive is the only thing below $100 - it looks cute with all it's meters, but it's a bit bulky
cheers, Tom
ps regarding pre-amps:
my 'main' bass is serviced to get new pickups, so I used another one I once had aquired because it seemed to be well crafted, but then didn't play it much because I just didn't get along with it's tone.
I can only say I really didn't expect the Radial pre-amp to make SUCH a difference

I definetely wouldn't have bought the 2nd bass (which is now modded for almost twice the amount I paid for it...) if I had played the first one through that preamp.
Fortunately both instruments feel and sound completely different, so I don't end with duplicate stuff
