Depends on if you want it done properly or not, for 3 grand i would bloody well hope you were going to get stuff like the bearing tunnel measured to a very close tolerance and then the tunnel line-bored etc, and everything spot on, bores that dont go thinner at any point, all that sort of stuff that 99% of engine rebuilds dont include cuase its too expensive, the general term used for a correct build such as this is a "blueprinted" engine, dont confuse this with one that is just reassembled with the blatantly broken bits replaced.

Saying "how much should a rebuild cost" is like saying

"I want to buy a new car and ive been quoted 14,000 is that a good price"

All depends on weather its an S class merc, a ford focus or a kia pride really.

Same with rebuilds, they are NOT all the same, not by a million miles.