Scooter economics

Ever since last summer, when gas prices were starting to get close to $4/gallon where we live, my husband and I have been thinking about purchasing a scooter. Since we seem to have a knack for living within a mile or two from at least one of our jobs, it seems like it could be a good investment that saves a lot of money in gas. Let's do some math, shall we?

Original investment: approx $1,200 (let's make it $1,500, to make it safe)
New licenses with motorcycle clearance: $70 (for two)
Insurance: I have absolutely no idea and I can't get a quote without giving every ounce of personal info I can-- we'll say $200/year, since that's about what I paid on my last car...
Registration: $100 (again, high-balling it)
Total: $2,070

So that's a hefty start-up cost. What will it save me?
My car gets about 24mpg and my husband's gets about 15mpg. We will say that the scooter gets 75mpg. It is a safe bet to assume that he will drive my car more if I have the scooter, but let's run the numbers both ways.

Our vehicle budget is $300/month. Assuming we each use equal parts for gasoline, that would put us each at $150.

My car gets24 mpg. 24mpg is approximately 1/3 of 75mpg, thus we can assume that I would save 2/3 of my part of our monthly gas allowance. 1/3 of $150 is $50, so I would save $100/month in gas by riding the scooter or $1,200/year.

Hubby's car gets 15mpg. 15mpg is 1/5 of 75mpg, thus saving 4/5 of his monthly allowance if he drove my car instead. 4/5 of $150 is $120/month saved by the scooter or $1,440/year.

Not bad, not bad at all. The scooter would pay for itself in about a year in this scenario. Especially if we deal-hunt and get a good scooter for under $1k, find good but inexpensive insurance, and we find that I've grossly overestimated other costs (which I usually do). Just dropping the initial cost of the scooter to $1k means the whole shebang is paid for the first year.

Not everything is oh-so cut and dry. I would drive one of our regular vehicles in the event of inclement weather or any time I have a lot of cargo to carry or need to use the interstate. (I am intentionally looking for something about 150cc so that it can go as fast as I need it to without going fast enough to really take it on the highway.) Not driving the scooter exclusively cuts into the actual amount of gasoline savings. Another year of skyrocketing gas prices could put saving over the top. There are plenty of what-ifs to think about.

I happen to have just about enough cash to pay for a nice, used scooter outright. Would you spring for it? On top of the economic benefits, it seems like a ton of fun! Soon my new-to-me car will be paid off (approximately 6 months into a 60 month loan... forgive the minor bragging...) and come fall if/when I'm working right down the road it could be a good thing. I hope to have some discussion on this one-- I really want your input.