You can send it out, but it's pretty easy to get them clean. Sterilizing is a whole other ballgame, though.
What I do with estates is the following:
Assess the stem for oxidation. If it is light or non-existent I simply run alcohol (high proof liquor or 91% isopropyl) soaked bristle cleaners through the stem until they come out clean, then give a few regular cleaners a go. After this, I give the outside of the stem a good wipe down. If the stem is highly oxidized, I'll use soft scrub cleaner and a cloth to clean the stem until the oxidation is gone then I'll buff with a dremel to restore the shine (you must be very careful here, you can easily burn the stem with the dremel). If you have a low speed buffer and tripoli you can use that to shine it back up, but you must still be careful as any buffing can ruin markings and logos.
After the stem is finished, I go after the bowl. If there's cake I ream the bowl to bare wood or pretty darn close. If there isn't any, I double up a pipe cleaner soaked in alcohol and wipe out the bowl. DO NOT GET ALCOHOL ON THE OUTSIDE OF THE BOWL. It may (very likely) damage the finish. After that I take pipe cleaners and clean out the shank the same way as the stem (this may take many, many pipe cleaners).
After that I take a damp (barely damp) cloth and wipe down the outside of the bowl to get the surface junk off, reassemble the pipe, and then I wax it with Paragon wax.
A pipe retort can be used in lieu of all of the pipe cleaners, but that's a pretty specialized tool.
Bottom line, if you're handy at all and want the experience, it's not tough. If you just want it done and you can wait for the turnaround, send it out. If this isn't something you see yourself doing often, it may be best to send it out if you don't have the tools and equipment needed (although they can be had for about the same price as sending out a few pipes).
This is not the only way or the "right way" to go about this. It's just the way I do it.
Good luck!
