I’ve done them for free depending on the customer and situation. Some take a few minutes; others longer. Some are easier to clean when pulled apart. What’s your time worth to you?
Most lantern style light fixtures will have the top hinged and held in place with a screw or the top can be entirely removed by removing two screws. A few have a door that opens for access to the inside. Do not remove the glass from the fixture. It is usually held in by metal tabs that are not that durable. The easiest to clean are the ones with the hinged or removable tops. I usually quote a price range on fixtures, subject to actual inspection. For these I would quote $15 to $25 each. Hope this helps.
The light fixtures where the panes of glass come out are the best. Yes, some have metal tabs and require caution but there are many that just slide into virtually indestructible metal grooves.
I then take these pieces of glass out and clean them all at once in the back of the van using Spray Way glass cleaner… scrub with a terry towel, dry with a surgical towel, and detail with a second surgical towel. The ones that can come apart like this end up looking brand new… I attached a picture to show one recently. If they do not come apart, use the same process but just do it with the glass in place. Just be sure the light is secure; keep a hand on it to hold it steady.
I only charge around $6-8 each for these, when you do more than a couple at once they go very quickly.
It really depends on the style of fixture. If you have a Fixture that has a rod that goes through the center, I try to remove the top to clean it that way. If its the kind that has those round thingys that hold the whole thing together, I disassemble it plate by plate.(dont do too many of those). If there are a ton of bugs in there, I whip out the Stihl blower and blow them out first. I then spray the inside with Sprayway foam glass cleaner followed with a 0000 steelwool pad. Wipe it with a huck followed by a clean huck to grab any left over smears and bug guts. Seems to work out well this way and have never had a complaint.
I like washing exterior lighting. Until you bust open a bee’s nest inside and you can’t run away fast enough looking like some idiot slapping himself in the face trying to get his headphones to turn back on.