Just in case you've never noticed this, HLJ has a sale page that's a wonderful source of cheap goods, including several Shinki sets.

They recently put up a slew of Microman figs. Sadly those arent DIRECTLY compatible with shinkis, but you might be able to pick up some parts for kitbashing. Also, a whole bunch of older Transformers stuff.

http://www.hlj.com/hljsalepage.html/