I have got to a point where I can breeze through them easily, so I have a different deal worked out now where I just take care of all of them, and trade out, but when I use to charge per cue, It was around 6-7 bucks. Believe It or not If you get a enough of them to do, then even at that price they add up quickly. The main thing don't let the work become priority. I don't even touch them unless I have at least 5-10, or more of them to do at one time. I think that's the point some are making here, the first couple may start out slow, but If you have enough to do in one sitting, you start to get in a groove and really breeze through.
I get all kinds valley, dufferin, imports You name It, so when I get a batch, one thing I like to do is group them according to the thickness, so that I don't have to keep changing collets until I run into another group of diameters. There's other little tricks too, like I replace them with lepro, so what I try to do is keep a stock of boxes of each size, that way I can match the tips close enough to the ferrule sizes, that all I have to do is crown, and trim the sides with a utility knife. The tips also finish off better and play better when You match them according to ferrule size, so It saves time in other ways too. I've noticed that a lot of those tips that would go bad otherwise, and have to be cut off to start over with another tip may work well for house cues, as long as You match them close enough that You stay in the layer that is tanned, and not have to trim down into the fluff. Another thing that helps with those fluff tips to firm them up some, is when I burnish the sides of the tip, I also burnish the crown, then lastly I come back with sandpaper on the crown to smooth it out, and so that It will hold chalk well.
Like someone mentioned re-tipping is kind of mindless work If you have a system that works for You. And You don't have to spend as much time as You would with a customer cues. I mean You still try to do good work across the board the same, but truth be told most house cues see far more damage in house, then the average repair guy with half a bucket of knowledge could do to them, so you don't have to be quite as careful or move as slowly.
Changing Ferrules though that could be more challenging, and take longer, because as someone mentioned most house cues I see are also warped, and putting a ferrule on them requires much more precision that takes more setup time per cue to get running true enough.