My March Budget...putting it all out there

We have been hit with a $2500 car repair bill this month, so this will be a complete no-spend month. The car will be sitting at the shop until we have the money, which will probably still be a couple of weeks. We have expenses coming up in April that I'd still like to have the money set aside for beforehand, without having to dip into the bonus my husband will be getting on April 9. My goal is to pay all we need to pay this month, plus have the extra we'll need for the first half of April...our 10 year old son is going to Italy with my brother, and I'd like to have all his spending money set aside on top of everything else. He leaves April 13, so we'll have the bonus in time, but I'd really like to have it way before that. We also will be spending the weekend before that in Chicago, which is where he's leaving from, so I'd like to also have the money for that, too. So here is the nitty gritty:

Income:
$2800 - my husband is paid twice more this month
$1004 - state tax refund
$877 - money back from our health savings account for dental work and glasses we got last month
$343 - balance in checking
$644 - balance in savings

$5668 - total in for the month

Expenses:
$2500 - estimate for car repair
$155 - motorcycle payment
$35 - credit card payment
$65 - Direct TV
$25 - flute payment
$700 - April mortgage
$207 - prescriptions
$99 - trash bill (6 month payment)
$488 - car insurance (6 month payment)
$211 - car registration and license renewal
$300 - gas (the dead car left us with the gas guzzling Durango for my husband's commute)
$130 - gas (house, our heat is gas)
$85 - electric
$75 - phone/internet

$5075 - total out

That leaves us $593 for everything else. I have given myself a $20 weekly grocery/household budget. I have both freezers full and a fairly nice stockpile, so this should be do-able. I'm counting it as $100, because I'm also including the first week of April in this budget. That takes us down to $493 for 5 weeks of incidentals...on paper it looks ok, as long as we stick to our no spend vow. However, this has to include Easter baskets, a school carnival, and a promise we made to the kids...my husband is taking the boys to a movie on Friday afternoon, and I'm taking my oldest daughter to the salon for her haircut. My son will also need some new shorts and a pair of shoes before his trip. It will be tight, but I think we'll make it. I also will obviously not have all I need for Chicago/Italy, but I'm going through all the clothes and stuff in the house and doing some long overdue listing on ebay and craigslist. I'll chronicle our daily journey on our month of being broke, including our daily menus. Cross your fingers nothing else comes up!