I bought three Revere fluted poles from another collector friend in North Dakota a couple years ago and dragged them home to restore. At the time I paid $450 each for them (unrestored) and that was a smoking deal with porcelain shades included. Shades alone go $250 to $500 depending on condition. Poles with the three or five bulb light fixture atop the shade, I have seen them go $1500 each in unrestored condition and they are very heavily sought by oil and gas collectors. You may get lucky and find a lone shade for $300-$500 depending on condition? I'll keep an eye out for you.
These are the 3 that I restored and put on the pump island in my garage. The wireless remote turns all the lights on/off which is a nice touch.