What would be the average cost to replace the engine?

CURRENTLY LOOKING AT THESE SLUDGE PROBLEMS AS MY MOM'S 2003 TOYOTA SIENNA 3.0L VAN JUST GOT A NEW TIMING BELT AND VALVE COVER GASKETS AT THE COST OF $1301. WHAT PISSED ME OFF THAT THEY DID NOT CHANGE... THE IDLER PULLEYS... NOR THE TENSIONER, NOR THE WATER PUMP... WHICH 100% OF 7 SHOPS I CALLED WOULD HAVE DONE... IF YOU ARE GOING THAT DEEP INTO THE ENGINE!!!!!!! COST IS ONLY MINIMAL AT THAT STAGE... AT 92K MILES THEY SENT ME HOME WITH PICS OF THE SLUDGE INSIDE THE VALVE COVERS AND PICS OF THE TOP OF THE HEAD WITH A NASTY SLUDGE BUILD-UP... AND THE OIL LIGHT IS ON CONSTANTLY!!!!!!! WHAT??????? I WAS SHOCKED AND TOLD THEM WE HAVE ALWAYS CHANGED THE OIL AND OIL FILTER EVERY 3000-3500 MILES FROM THE TIME MY MOM PURCHASED THE VEHICLE! DID THEY DO A MECHANICAL OIL PRESSURE TEST? NO! A DEALER NOT DOING THAT? WHAT? R U KIDDING ME? LOL! NOT FUNNY BY THE WAY! THEY SENT ME HOME WITH AN OIL LEAK WE NEVER HAD! ONLY WAY I FOUND THAT RITE OFF THE BAT IS THAT I WAS UNDER-NEATH THE VEHICLE TO DRAIN THE OIL. HMMMMMMM! DESERT TOYOTA IS NO LONGER TRUSTED IN MY FAMILY HERE IN TUCSON, AZ. THIS IS BULLSHIT! KYLE BROOKS IS NOT THE HONEST, I GUESS HE'S THE SERVICE WRITER, SO CALLED PERSON HE CLAIMS HIMSELF TO BE. NOR ARE THE MECHANICS THAT WORK THERE! I SEE NO HONESTY HERE TODAY! I AM F***ING PISSED OFF AND ANGRY THAT THEY TRIED TO TAKE ADVANTAGE OF MY ELDERLY MOM!!!!!!! SOMEONE IS GONNA PAY HERE!!!!!!! I AM NOT ONE TO GO AWAY WITH THESE IDIOTS TRYING TO WALK ALL OVER MY MOM!!!!!!! GET READY DESERT TOYOTA AND KYLE... CAUSE I'M NOT GOING AWAY WITHOUT YOU FIXING MY MOM'S VAN PROPERLY... OR YOU WILL GET SLAMMED WITH INTERNET MEDIA THAT YOU WILL NEVER RECOVER FROM... DO THE RIGHT THING HERE BROTHERS!!!!!!! NOW!!!!!!!

Depends on if it's a used engine or a re-manufactured engine. I would estimate between $2,500 & $4,000.