In my opinion, those are not the kind of products which will be good collectors' items as their value won't increase much over time. As a matter of fact, it most likely will decrease.
It should be said that Sansui had a sad demise (I think they may still exist, but not really).
I'm not sure what happened, but somewhere around the mid 80's it seemed they were being milked for their reputation by selling low quality products at medium quality prices (after developing a reputation for high quality products at medium quality prices) under the Sansui name. The previously good Sansui name quickly converted to a reputation for crap.
My point is your comments are far too generous if they refer to the latter Sansui products!
I'm pretty sure their flagship amps and receivers from the "golden" years bring a decent profit (but nothing like a top level McIntosh). I say profit in absolute dollars, but if you adjust for inflation, they are probably not really returning a profit.