Stand Alone E-commerce Software for an online store

I have tried many standalone stores and I bought a few from some programmers on here and nothing but trouble with them in one way or another. Does anyone know of a good complete Stand Alone Online Store Software?
And I have a pretty tight budget! I need something that will work in Canada and tie in with Canadad Post.

OpenCart or PrestaShop are solid options for standalone, budget-friendly stores. The base software is free to download and host. You'll probably need to purchase an add-on or module for Canada Post integration, but that's typically a one-time cost. They generally work well in Canada.