Hi Marama,
Congratulations on the success you've experienced so far. It's awesome that both you and your wife are working on it as a team; so many people can learn from your example.
Unfortunately, Blogger does not give you the option of setting up 301 redirects. A 301 redirect would tell the search engines that your blog has moved to a completely new site, so start assigning credit to the new page and update the index with your new links.
Because of this, you may end up losing your current rankings in the search engine if you completely move your blog to your own domain, or even use Blogger's domain mapping feature.
As Linda already mentioned, no one can make the decision for you, but it's a good idea to weigh your options and decide accordingly. A while back, I wrote an entry called
From Blogger to WordPress: Import or Start Fresh? which deals with exactly this topic.
Instead of rehashing the whole article here, it mainly covers what I mentioned above, what to consider before making the decision, and if you do decide to start fresh on your own domain, it offers some tips for making it a smooth transition.
Wishing you plenty of continued success!
~ Teli