I've been informed that there are no low cost Chinese replacement parts for (68000) chips.
I read some time ago (but I can't find the link) that freescale does licence the ip of their chips for manufacture by third party. As a matter of fact back in the day motorola licences the 68000 to Hitachi, Mostek, Rockwell, Signetics, Thomson/SGS-Thomson and Toshiba; so it would be feasible to produce low-cost replacements if the demand justifies it. I am surprised to hear there is no one in china already producing 68000 chips since I think I have seen some toys with "16-bit graphics" that resemble some sega genesis games.