A fair price as compared to what? There are a lot of shops that install sleeves. There are thin walled sleeves that are cheap and thick walled sleeves that cost about $50.00 to $75.00 more than the thin walled sleeves. There are shops that take the time to do the job right and there are shops that rush through the job to try to compete with shops that advertise their services on Ebay. It cost more to install a thick walled sleeve because of the additional time it takes to machine out ALL of the original iron sleeve and the additional time it takes to match the ports on a thick walled sleeve. You can spend anywhere between $150 to $350 for the sleeve and the labor.
Find a shop that has the proper equipment for the job and machinist that will do the job right