(W)MD20RLT can be had at most aquatics (ponds, etc) dealers ; the 20RZT is a bit harder to find, though
www.customaquatic.com has them (dunno if they ship to canada). as for noise levels, i don't know.
the AQX 50z can be had at
www.cooltechnica.com. dunno about shipping to canada and i don't know about noise levels (though i think its fairly quiet).