"Am Canadian so handguns prices are inflated due to the incoming import ban."
Having lived in Canada, I feel your pain.
In a way, the question of value under the current circumstances is an abstract one.
If the gov't up there is serious about the ban, and demand outstrips supply, then the price is whatever the market will bear.
On the other hand, I do know this since I still have family there: There are people wanting to unload their stuff because it's "now or never"! If the ban happens the only option to liquidate will be to turn it in to your Regional Firearms Control Officer.
If you have first hand contacts it is possible to track down amazing finds for next to nothing.
Depending on your point of view, you may want to ask yourself:
"What will this be worth when there's no way to sell it?"
If I understand the proposed ban correctly, you won't even be able to export it.
About the ammo, all current production .455 ammo is an imported commodity in Canada, and all imported ammo in Canada needs an import permit. The Federal gov't there decides a year in advance the quantities and types of ammuntion, powder, and primers for which import permits will be granted.
Will importation of hangun ammo therefore cease to coincide with the ban?