Well since you are in Canada & I am assuming your business & banks are also based in Canada, I would suggest to check out PSIGate or Paysystems.
Now - what shopping cart are you going to use? PHP or ASP?
Do not apply for a merchant account until you are ready to use it (unless you are not charged on a monthly basis). No need to pay for something you do not use. We get about 10 clients a month who want to get their merchant account - yet they do not even have a website. I always tell them to wait.
First step - get a domain name. Then get someone to design / develop the site. Find a hosting company that suports the language that your cart was built in. Usually PHP is in *NIX flavors & ASP / .NET is on Windows. Most gateways will give you a test account to test your settings & connectivity. I would also get an SSL cert.
Now you already have your inventory, right? Apply for your merchant account - get approved & your set to go.
Make sure that PSIGate or PaySystems will approve your account for adult DVD's, etc. as well before moving too far towards integrating into them.
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Here are their websites: http://www.psigate.com/ & http://www.mypaysystems.com/. I would send them an e-mail and ask them if they support the type of products you are selling. Being in Canada - it might be a little more difficult. The banks up there do not support a lot of high risk (adult - video text, etc) services.
I tried to search for chinese shopping cart but nothing came up. What language are you looking for the cart?