Apart from all the other question marks raised by this, I'm curious as to where you'll find all the custom chips needed. There's not exactly a cheap Chinese production line on standby for manufacturing SID and VIC chips. If you want to buy up and slaughter old consoles and computers for spares, you'll hardly become popular in the communities and besides, these machines are getting increasingly scarce.
I'm afraid going into retro hardware is hardly a place for get-rich-quick-schemes. Most people doing advanced hardware stuff like this are driven out of a passion for a certain platform and I'd be surprised if you could find more than two or three persons world-wide who've managed to earn a living from it for any substantial amout of time.
For the record, I have spent much of the last year purchasing stock from China (which is still a happy hunting ground for old chips -
IF you can find the decent sellers) for my repair service.
After a great deal of time and money (measured in the thousands of dollars) I have a total of 51 SID chips that fully work, about 50 C64 CPUs, 50 C64 CIAs, 10 VIC-II, about 20 8501 CPUs (C16/+4), 20 or so 8360 TEDs (also C16/+4), and various other chips such as old RAM chips, MC6845 CRT controllers, that sort of thing. I have 8 PAL VIC I chips (for the VIC-20) with another 50 on the way, and 9 NTSC VIC I chips.
I can tell you now the chances of getting a regular supplier of these chips is zero.
Mostly because I've bought most of them.
Even the ones I found though have had quantities of about 50 pieces maximum - nowhere near enough for a full production run of a console using them.
Note: In case anyone's worried about me stopping anyone else from buying them by buying them all, remember these Chinese places have a minimum order quantity in the hundreds of dollars, charge about $50 shipping (courier) and often don't take PayPal... and of course many of them are scammers who don't actually have any chips but just take your money and run.