A new transmission filter and gasket set costs between $30.00 to $80.00 depending on the type of vehicle.
Then the transmission fluid can cost up to $30.00 to $50.00 depending on how many quarts of transmission fluid your vehicle takes.
Some vehicles take more transmission fluid than others.
Now if you have a shop replace the transmission fluid and filter it can cost around $150.00 to $250.00 depending on the shop who does the job and the shops hourly rates.