Jordan has gotten quite expensive recently - the prices in your guidebook will likely be wrong by a wide margin… e.g. often the prices are double those listed in the latest Lonely Planet book. For hotels it is only up by 40% or so, but fuel has risen 10x in the past 6-12 months in the country.
In Jordan, if you are half-way fit, do not miss the hike up Wadi-Mujib near the Dead Sea. You walk for about an hour in a stream of water (upstream going in), through a narrow gorge. On average it is about 12-18" deep, and the gorge is perhaps 40-50 feet wide and 200 feet deep. Amazing. It was the highlight of my trip.
If you plan to travel to other Middle Eastern countries, cross to Israel at the King Hussein bridge and back the same way - ask the Israelis to not stamp your passport (they might still do so).
Stay in Madaba instead of Amman - it is cheaper, less polluted and closer to the sites along the Dead Sea.