If it's just a display piece there are .177 MP5's available in Canada for dirt cheap too.
MP5K PDW: http://www.dlairgun.com/Air-Rifles/Heckler-Koch/
I'm 99% sure I've seen a standard .177 MP5-A2 or something like that but I can't recall exactly where.
As for the 416 I have no clue but Anschutz makes an "AiR-15" that's more like a M16 than anything. Only problem is that you can't really modify it since the handguard has a CO2 tank in there. Your best bet other than that is probably to get AV'ed and snatch one up. Hell, if it's just for show then buy a broken one and have it up on your wall or whatever.