Baby Needs A New Roof

We received an estimate to have a new porch roof put on, and also repair the roof over the ad-on, which is where I work. My father-in-law said he thought it would cost somewhere around a thousand bucks, but these guys came back with (gasp) $5400.00. Needless to say we're getting a couple more estimates. I had not budgeted enough for such a huge expense, but now, before we even get the other estimates, I'm trying to calculate how we can work that in. That way, if it ends up costing considerably less, we'll be ahead.