I broke all my valve guides & stressed the pistons when I did my waterpump. I found A used engine for $1,300 with 78k. I was told $2,800 for eng./parts/install. Is this a good price?

 

Damn that is very bad luck I feel sorry for ya. I'm going to assume you have a VE. $1300 seems on the high side since I've seen lower mileage VQ's sell for that and cheaper. As for labor it should be anywhere between $800-1600. I would suggest getting all oil seals (front and rear main), water pump, drive axle oil seals replaced while the motor is out. Now if you were a VG $1300 is way to much, used VG's run for around $400-900 depending on mileage. If possible ask for a compression test on the motor you want to buy.