Agree Joe's ballpark figures for accommodation - they can vary as well by location, as well as what you get. Still some wonderful value out there.
n.b. I've used our decimal for currency, but you'll see the Italian write €3,000.65 as €3.000,65
Meals? Again this can vary, but let's say:
- Breakfast included, but on the occasions it's not, go Italian and have a coffee and a pastry for ~€2.50-4 each
- Light meal of the day (be that a panino and a soft drink, or a plate of pasta/risotto, or a light meal plus wine in an enoteca) let's say €7-€20 a head
- Main meal of the day (from pizza and beer in a simple pizzeria found all over, to an agriturismo banquet often at a giveaway price, a simple or fancy trattoria or fancier / scenic restaurant) let's say €15-€60 a head
Add in a gelato or two - let's say two @ €2.50 each, so €5 a head
Plus anything else from fruit to an additional coffee stop or an aperitivo (~ 6-8pm) drink and free nibbles. Let's say an average €10 a day
Savings can be made if you get an apartment, or just plow the savings back into grazing the wonderful food shops and keep a moveable picnic feast going for the light meal of the day / breakfast.
Fuel worth factoring in it looks like it's around €1.70/L for unleaded
Often free parking available, especially away from the big cities, so it won't be everyday. Maybe a little for buses/trains/boats when you want a day trip without the hassle of the car. Let's say €5-10 a day for all that.
Toll roads, plenty of small fee (motorway) toll roads - maybe €5 a day for the car
If you like wine, then Italian wines are a bit pricey in Australia, but coming sown a little as interest grows, but it's a nice treat to splurge on that you can enjoy back at home and remember the holiday when you drink it.If such things appeal, maybe a couple of bottles apiece crammed into luggage, wrapped in a plastic bag and then clothes (dirty or otherwise!). Anything from €40-€100 a head if that appeals. p.s. if beer appeals more, the Italian brewing scene is pricey but wonderful - well worth hunting out the niche brews as against the ubiquitous lager styles which can refresh the body more that the mind.
Clothes / shoes. Some great stuff, and easy to bring back. Depending on whether this interests, maybe €50-€200 budget per person for the trip
Entrance fees for museums etc. can vary let's say €5-10 a day average
I'm sure some of these will end up poor estimates, but hopefully give you some sort of ballpark and I've not missed too much obvious stuff