The 2x2 Ipe lumber stock that comes from your local lumber yard has to be cleaned of all the dirt and soot and scratches and wax deposits. Otherwise, your stain job will seal in the dirt and be blotchy ugly. It takes time and energy to sand an area 1-1/2" x 12 feet (2x2-3' all 4 sides). It costs money for labor, the electric is not free, and the Ipe does go through it's fair share of sand-paper.
A typical deck job may easily have over 100 ballusters. To bring those ballusters up to snuff, here's what I do.
1) Change both rolls of sandpaper in the drum sander for every deck job of 100 ballusters or more. (Pain in the butt - easily takes 1/2 hour to an hour and uses about 40 lft of roll sandpaper)
2) Look over each balluster and scrape off the large wax deposits so it doesn't clog the sandpaper.
3) With 2 people - one feeding one catching and returning; run them through the drum sander. Turn them over and run them through again, turn them over and run them through again, and finally turn them over and do the 4th side of the balluster.
4) Bring them over to the mitre saw and cut the 7 degree bevel on the one end.
5) Set up a stop and precision cut them in length to the finished balluster height. Very important that all is to the exact same height.
6) Touch sand both cut ends of the 2x2's, get rid of any roughness so that the stain rag won't get snagged.
7) Bring them over to the staining station - hand rag stain them - stack them over in the drying room with stickers between all rows with fans blowing them dry.
8) Wait at least 1/2 hour and then with clean rags, wipe off the excess stain.
9) Stack them again with stickers - and cover them so they don't get dusty.
10) When you order them, we pull them out, bundle them with shrink wrap and put in a plastic bag to help keep them clean while on the job site.

So now that you know what goes into finishing Ipe ballusters, I can better justify my prices. You can do these yourself, or have your contractor do them for you. But I'm pretty sure that if you take on the job yourself, the next time you'll have me do them from the start.

You would be surprised at the amount of dirt and grime and wax and scratches, that you will find when you purchase your 2x2 balluster, 4x4 post stock, or 1x6 wrapping from the lumber yard.

By the time you set up your work areas, go buy new belts for your belt sander, (I sand them with 100 grit then 150 grit) put a new blade on your chop saw, and go through all the motions that are needed to have fresh clean wood before you stain them, it would probably take you at least a full day's labor. Then add another 1/2 day for staining and drying. When all is said and done, from set up to cleanup, you should allow 2 man days for preparing your posts and ballusters.

The decking contractors who think they can save a buck by doing it themselves, will usually only do it once. The next time, they have me do it