Hey Garry… I charge $20 for ceiling fans with no lights and $25 for the fans with lights.
I have never timed myself to see how long they take (I guess 5 -10 minutes max). I usually clean them once a year. They are never really that dirty after the initial clean. This is for only a few houses. I don’t advertise that I clean fans.
I do have a minimum service charge of $75.
For regulars that are close by I will do minimum of $50 for screens, money windows (high traffic windows), or gutters.
My thing about the ceiling fan cleaning was not as a stand alone service to drop by and clean a couple fans, as some I think misunderstood; it was as an ADD ON SERVICE to be in addition to window cleaning just as mirrors, screen repair, and most gutter cleaning is.
With gutters I think I have had maybe a half dozen jobs in the last year that were solely for gutter cleaning alone. Most gutter cleaning jobs are in addition to window cleaning.
Just for clarification folks, when I post up about additional service? It is just that, add on services as my window cleaning service is the major job that gets me in the door.
Great add on! It adds 20 to 30 bucks per job and takes very little time.
We charge 25-30 dollars also for the service its a simple add on service, we dont do to many but hey 25-30 extra while your there, it all adds up.
Thought I’d revive this post, I’ve been using the Unger Pro Duster all year:
Threads standard, microfiber head is washable; works beautifully. Move precise enough and the falling dust/debris is minimal. I bring a sheet along, if it’s over furniture I quick drape it and get to work.
As @Garry mentions above though, definitely an add on situation.
While cleaning windows I throw an eye on their fans, offer the add on. Just yesterday, 3 fans, vaulted 2 story ceiling, $25 a piece. $75 for 15-20 mins of dusting.
The added bonus is the reaction from homeowners; how are they going to clean a fan 20-25’ up in their finished home?
They were so happy to have em done and safely without damaging surfaces, they gave us a $25 tip. 
The Unger Pro Duster is an $18 investment, you support WRC, make major add-on bank and keep your customers happy…
It’s a winner IMHO. 
Many times fans get so neglected. The dust that accumulates on the fan blades actually slows them a wee bit and puts a burden on the fan motor - i.e. shortening the life of the fan. Using that approach with the customer to sell the add on cleaning the fans is a no brainer. But gravity and the slightest air flow makes the dust go all over. I have resorted to using a pillow case slipped over the fan blade and wipe the dust off inside the pillow case. (Drop the pillow case in the wash and done; you can do multiple blades this way before cleaning the pillow case). Some furniture polish on the blades and clean the housing and it looks great and the blades move the air more efficiently. The little extra that you do makes the price you charge seem more valuable to the customer. The blade cleaner attachment can be subsequent cleanings - just a simple wipe on the next visit — Oh yea! Try to sell maintenance visits. It is like the “rental business”, sell the same thing over and over. 
$5-$15 a fan. Outside fans are more expensive. I will not touch decorative paper fans ever. Kitchen fans are the worst. They command extra $$ due to goo-off for the 7 layers of kitchen grease. Sometimes I just pass those and move on.
