For the rail adaptor, there is two brands that are good enough, GG&G and Surefire. The Surefire is a little more sturdier, but pricey. The GG&G can be found here for the USP Compact:
http://www.wolverinesupplies.com/det...ght-Mount.aspx
For the suppressor, you need something with 16mm threads, which is quite rare. The only two options are custom made cans, or the MK23 specific suppressor which uses the same threads. One brand that offers both custom suppressor and adaptors is Lees Precision Engineering:
http://www.leesprecision.co.uk/
They ship to Canada, but I cannot guarantee you that the customs will let the suppressor pass. The adaptor is safe and solid, I own one myself. You may want to invest in a thread protector as well, since you will already pay the shipping, the do protect, and they look badass :P