First, and most importantly, Belrain -- where are you located, exactly ? Next, most likely you will be nailed for duty (not so much) and taxes (GST, anyway).
As far as Happ stuff goes, Starburst (now known as
Playdium) is the official distributor for Happ in Canada. You can disregard the online catalog as they provide most of what Happ has, even if it isn't shown in the catalog.
If you want to choose between Groovy Game Gear and Ultimarc, make your choice based on technical specifications -- I order from Ultimarc fairly regularly and there really isn't any penalty for ordering from the UK over ordering from the USA. In fact, I prefer to order from Ultimarc -- shipping is lightening fast (faster than when I order stuff from the USA) and I never get dinged for excessive brokerage charges.
jan25th is right with respect to UPS (and, say, Fedex ground) ... bad brokerage charges (taxes and duty should be independent of the carrier).
If you are looking for specific things, or perhaps just a cabinet to plant a PC in for MAME, check the forums at cgcc.ca (Coin-Op Corner) or maaca.org.
Both sites have members in the East end of the country and a number of members may have the stuff that you are looking for (they may not want to sell it, but it doesn't hurt to ask).
Here is a must-read guide for folks looking to import coin-op-related stuff into Canada:
http://www.cgcc.ca/forum/viewtopic.php?t=7594&sid=8a8afefbc24b3c1652e717e87e355041I am a big fan of USPS/Canada Post for shipping stuff -- relatively fast and very fair brokerage fees.
EDIT: It is not uncommon to receive an invoice for brokerage fees/duty/taxes several months after the order actually arrives (I got a bill for a monitor 14 months after I received the monitor), so be careful believing folks who say that they didn't get dinged ... although that does happen.EDIT2: In case it sounds like I am saying to avoid ponyboy or divemaster, that is not the case. Just check with SB first -- for some items, they are better on price and for some they are not, particularly when you factor in shipping. I have had folks ask me to pick up an order from SB (the old location was about 16 blocks from my house) and then ship it from there.