I just give a total price,I calculate how much mulch,estimate how many hours to lay,add extra to allow for mistakes and that's my price. I think laying mulch is a lot harder than mowing lawns so I want to make sure I get well paid for doing it.
I have to see the job. To get a prep cost. & the cost to apply mulch.
You can have a place that uses 3 yards. Full of perennials. That you have to hand place the mulch around the flowers . That it takes twice as much time to complete.
Another property is wide open. You can still see mulch from last time it was mulched. All it needs is colored. That you just throw it .
Then you have open again. But it is all dirt. Where you dump the mulch from the wheelbarrow. Spread with a rake.
Then you could have hard to get to spots. Like the top side of a wall.
Only way to get it there. Is filling & lifting garbage cans or buckets.
Myself I walk around the property a few times. The first is looking at what needs done in areas. Adding the time as you go around the property.
Some can be a hour. Every 5 steps. You take.
By time you trim a shrub clean up trimming , pull a couple weeds. Then edge. Dont forget the small tree ring. That's automatic a hour. You may have lots of roots to put a edge on it.
The second walk around.
You walk around judging how much mulch is needed. By How far can you get with that yard. Adding up as you go around. Now you know how many yards is needed. Every yard. Pretty close to a hour. To apply & post cleaning.
Till you get the eye. To hit your target add a yard & another hour.
And simply say . You bid it on the high side. so no surprise at the end.
Do not be afraid to be high on the bid.
My area. There is 3x as many mowing only guys That . Getting mulch jobs are easier to land .