My expertise on delux accomodations, however you may find cheep accomodation anywhere between 10 Usd to 25 Usd. both cities. Food you could fix anywhere between 3 Usd to 10 Usd. depens where you eat ofcourse. Drinking & nightlife can be a bit more expensive again depending what kind of clubs you attend. In Antalya if you go to fancy clubs a beer would cost 3 Usd. modist bars are still selling for 1 Usd. You have to shop around a bit to find the best suitable for you.
Have a lovely time in Turkey.
We recently stayed a week in the Old City part of Antayla for 25million a double with breakfast (per day)at the White Garden Pension - was just a top spot. Plenty of other pensions close by.
Antayla was a great spot to cover many areas of the Western Med. The best part of Antayla was magic scenery but staying in the old city gave the best of both worlds. Through Hadrians Gate, the new vibrant city while a quieter, very historical world remains in the Old City.
Some top restaurants in the old city, could have stayed longer!