It's totally up to you and what you think will be best, but I can tell you what I would've done in your situation--
If your average isn't too far off (and even if it is) from what Sauder is asking for, try and talk to the enrollment manager or to contact whoever is responsible for admissions at Sauder. Phone them, email them, show them you really want this...be assertive. It could make a difference. A friend of mine with a low B average was rejected from UBC, sent them a very convincing email, and was then accepted! Most people don't do this and just take the rejection, so you'll have an advantage over them...it could work!
...but if it doesn't, I would go into a community college for business, work really hard for a year and get good grades, and then transfer into Sauder. You'll probably even get credit for some of the courses you'll take in the community college, and not have to retake them at UBC.
Hope this helps, good luck!