I'm in the Denver area and do it yourself, best price was 475.00 (rebuilt with warranty). Through a tranny shop was between 1000 and 1400. Rule of thumb is about the same price to install as it is for the part.
The answer to this depends on exactly what you are going to repair.
An Allison 1000 transmission will not bolt up to a Chevrolet 454 you begin engine. The Allison transmission is much larger than the Chevrolet engine housing can handle.
About 125 pounds
How does it cost to replace a 2003 tahoe transmission
how much trans fluid from empty to full
about one-three grand!
$237
How many quart of transmission fluid is requier for a Chevy impala 2007
Depends entirely on what is wrong with it.
The approximate cost to repair your automatic transmission would be $1,200 dollars.
There's a book entitled How to Repair and Modify your transmission available on Amazon.com. It is going for around $20 plus shipping.
I had to have my transmission range sensor replaced today and it was $207 for parts and labor.