Navona Notte, near Piazza Navona, is one of the best places in the centre for good quality and price.
In Trastevere head for Piazza San Callisto, and the pizzeria of the same name which has the biggest pizza in the city. The price is reasonable, and you won't have to eat again for the rest of the day.
For a sandwich Aristocampo in Campo dè Fiori isn't bad.
If you are really on a budget, but want a drink with dinner follow the street behind the church of Santa Maria della Pace until you come to a small piazza with a bar in it (its the only thing there). For the price of just one drink you can help yourself to the buffet that is served between 7.30 and 9.30 and includes pasta, rice, dips, bread, veg etc. then you won't need dinner.
Another cheap place to eat is in Parioli, and it's called Il Simeto (it is in Via Simeto!). It could seem a bad restaurant (old fashioned, small, the owner could even be rude), but food there is more than delicious: very large portions of pasta, good meat courses, and a wonderful pizza. All at a very affordable price.
The cheapest eat in the Termini Station : there is a little supermarket right beside the entrance near Marghera Street where you can get a cappucino and a pastry for 1 Euro. And they are excellent.
Great German and Italian food with excellent beer can be found at the Italian brewery, Birrera Peroni, near Trevi Fountain.
Be careful when you choose a restaurant. Don't just look at the menu prices. There is a cafe at the top of the Spanish Steps, just opposite the Hotel Hassler, and the prices for panninis were 5 Euros (about $7) each. However, a small Coke was 6 Euros (about $8), a small cup of cappucino was also 6 Euros, and a small bottle of water was 12 Euros (about $16). Lunch is not $25 for lunch for 3, but will end up being twice that. The drink prices were not listed on the menus. Many of the restaurants and cafes in Rome do this. Order the food, and bring your own drink, even if you have to drink it after you eat as you leave.
