I need to know if there are flights from Arequipa to Lima. I would like to fly it isn´t to expensive. If there are no flights, and I have to take the bus, how many hours would it be and the route....Thanks. I am not in Peru yet, but I would like to know before I get to Arequipa.

There are flights. Here's a good link for flights in south america It includes links for internal flights as well as flights flights to and from S Am
If you are curious about bus times: Peru Bus Times

Check the Ormeno site for times. It's a good run as you go on the coastal highway. Also.. that stretch has several very interesting places to stay if you have time. There are Nazca, Ica, and Pisco..with a trip to the Islas de Ballestras.

It's a long bus ride. Arequipa has a good number of daily flights to Lima and one way tickets aren't expensive (around $70 in LAN I think) so if you have the money I would fly back to Lima.
Just a tip...if you do decide to fly by LAN and buy your ticket on the web, make sure you compare the prices for tickets in both the Peru and the US website. Sometimes flights in the US or international website appear as more expensive (significantly!) I guess they figure the "gringos" have the money to pay more! :P haha.

We'll be flying with Aerocondor (from Lima to Arequipa). About $70 (tax included). LAN is a bit more expensive.

There are about seven flights a day from Arequipa to Lima - you'll easily find one that works for your schedule. $70 USD is about right for the price. The flight is no more than 60 minutes, the bus (though a beautiful drive) is about 27 hours. If you can stop off along the way, it's worthwhile. We stopped off in Nasca and then in Ica for Huacachina, and it was fantastic. Enjoy Peru!