The best option from Rome to Budapest is to take the Eurostar from Rome to Venice and then the night train from Venice to Budapest. The whole trip will take 18 hours. There is no direct train between Rome and Budapest. For example: there’s a Eurostar leaving Roma Termini station at 4:50 pm that arrives in Venice Mestre station at 9:06 pm. The night train from Mestre to Budapest leaves at 9:40 pm. The regular cost of the whole trip is 111.10 euro if you get 2nd class seats, 125.10 euro if you get a berth in a 6 bunk cuchette for the night train, or 132.10 euro if you get a berth in a 4 bed cuchette. However, there are some discounted tickets on this route at what is called the “Smart” fare. This will save you 26 euro on any of the above prices if it’s available when you want to go. I checked some dates in July and the fare is currently available.

Personally, I would consider going from Rome to Venice in the morning, store luggage at the baggage deposit at the station, spend a day in Venice, and leave from Venice in the evening. The same night train leaves from the Venice Santa Lucia station at 9:27 pm. The Mestre station is on the mainland – Santa Lucia is the station on the island.

There are also two budget airlines that fly from Rome to Budapest: Germanwings http://www.germanwings.com/index.en.shtml?gwcref=http://www.whichbudget.com/en/cheapflights.php?to=BUD and WizzAir http://wizzair.com/skylights/cgi-bin/skylights.cgi?module=SB&language=EN&mode=0. WizzAir has flights next month for 49 to 83 euro right now including taxes and fees. Flights to Budapest leave from Fiumicino Airport in Rome. The travel time is about an hour and a half.

If youre doing a bit of train travel a railpass might save you some money.

It will turn out most probably to be more expensive booking from Sydney. Much more expensive.
As simple as the idea sounds, I have done this myself; booking a ticket for my father from Moscow to Melbourne, and it turned out to be triple the cost then what he would have booked over there…So i’m telling you! DON’T DO IT!

It might look cheaper, but there are some regulations that some countries have, and they just pile on the tax etc for you when you book overseas because…its just way to complicated to explain on here.

You can try, but I’m strongly urging you to get him to book his ticket in Italy and then you won’t have to worry about anything. If you aren’t convinced, go to a local Flight Centre and book away with a travel agent.

Goodluck