There are a number of ways to get to Petra from Amman; the cheapest is the local bus which also takes the longest - about 3 hours. These go from the Wahadat bus station (ask the taxi driver for 'mujamma al janoob') to the south of Amman. The bus stop is on the far left of the station and the sign will read Wadi Musa in arabic وادي موسى. There's no timetable as the buses go when they are full. There are usually 4 or 5 a day though fewer on Fridays. This should cost you 7JD (perhaps more if you have a large bag) and can be quite fun, though a bit on the cramped side.

A newer option is the JETT bus service - these are air-conditioned coaches that run once a day from the JETT office in Abdali (at the top of the hill on the right), leaving at 6.30am. Call 00962 6 5854679 to reserve a place. this costs 9JD and takes about the same time as the local bus, but is more comfortable!

A taxi is a further option, though of course the most expensive - roughly 65-75 JD depending on your bargaining skills and the time of day. You can often find a taxi at the Wahadat bus station waiting to pick up people who are tired of waiting for the bus, so you can share the ride and the cost. This usually takes about 3 hours, depending on the driver!