I don't have any seeds for cold tolerant succulents but hopefully someone else can help there. It may be a serious challenge for you to grow even cold tolerant succulents outside in Vancouver, given the kind of winter rain you guys get. The really dangerous conditions are not cold alone but cold and wet combined, even worse cold and wet and dark. I know what winters are like in the Pacific NW after spending a few years there.
But if you have a sunny windowsill or similar then overwintering indoors should be quite easy.
Bear in mind that many cacti make tiny seeds which require years of nursing along under pampered conditions before they would be ready for the outdoors. (Again, that windowsill works great.) You will get off to a much quicker start if you can find a cutting (for example a pad from a prickly pear) that you can root... ready in weeks or months instead.
