It is going to be tough with a dog, but not impossible. There is the MLS search but would cost you money, or Craigs List.
Try Bay HO or Bay Park Area , Usually there is more there with yards, for the dog and 6 minutes by car to the beach.
Or Ocean Beach is more Dog Friendly with Dog Beach, and lower rents.................... more
Where is he going to school? That will help me steer you in the right direction. There are areas that have dense apartment complex and then there are areas where you will be hard pressed to find anything. San Diego is a big place so letting me know what school I can advise you better. Seeing he is in Escondido he might be going to school in San Marcos? If that is the case you might want to try Vista, San Marcos, Fallbrook and such. $800 is impossible I am sorry to say but $1k might be if he is resourceful. Also, beware of craigslist ads as out here many are scams. Google it and you can research that as well. Good Luck!... more