As a Canadian married to an American, you can move to the US once you secure a green card. You must apply for the green card in Canada at a US Embassy. You will need documentation on your marriage and will have to schedule a personal interview. Once you have a green card you get a Social Security Card and can legally work, live, run a business, etc in the U.S.
As for money, there are no requirements for money that I know of. Anyone with a green card can live and work in the US.
You don't need anything to buy a business in the US. If you want to work in that business - you need a working visa (TN that you can get as a Canadian citizen can do, you can apply for H1B which is a little less flexible, but more reliable once you get it, and your wife can petition you for a green card - if you intend to move to the US permanently).
If your wife petitions you for green card she will have to prove sufficient funds (which are pretty low, if you have the means to buy a viable business - you're probably there). For TN/H1B - the business will have to prove ability to pay.
Consider visiting Area 51 and committing on the Immigration topic, for a more relevant Q&A site to appear on stackExchange.