Great idea! I want to get a Saiga 12gauge so badly but it's a prohibited AK variant in Canada.
A VZ58 in 12gauge is a genius idea, make it compatible with Saiga mags, which are very plentiful stateside - in all sizes, even drums, and you've got a hands down winner.
I'd pay, $1000 - $1200 for one. I think this has even more sales potential than the .proposed .308 version, so far as I know there is no mag fed semi auto shotgun on the canadian market.
Just look at how popular Saigas are in the US, this is an untapped market here - business 101, supply and demand.