Why would you want to price it just high enough to make a tad more than your regular job. Thats whats wrong with people pricing things based on hourly.
Factor in your mulch costs.....Add labor. You have to assume that you can spread at least a yard an hour. Don't forget the time to pick it up from the mulch yard, and fuel for delivery, etc.
Now.....If your mulch costs you 22 dollars a yard plus tax, as mine does, then you know your material cost based on how much you need.
Labor....1 yard an hour ( I can spread 2 an hour if I hustle). If you pay a helper 10 bucks and you want to make 20 bucks an hour....(remember that now there are two people so you can spread more per hour), you know your cost for labor
Now, if you and your helper can spread 3 yards in 2 hours, you have 22 a yard plus tax (70.46 for 3 yards based on MY tax rate here), plus 60 in labor.
NOT factoring in anything else except labor and material, you are looking at charging about 43.50 a yard for mulch. This didn't include your time getting it, or a delivery charge, or your cost for fuel to get it (depends on how you get it to the job site) IF you have it delivered, small jobs cost you more than big ones. (I can have UP TO 23 yards delivered in one trip at a cost of 55 bucks, but I can have 1 yard delivered for that same 55 bucks....see my point?)
Then you have to figure cost of the tools you need to spread. Do you need a trencher? 100 bucks for rental for a day. Shovel? Wheelbarrow? Rakes? Tarps? blower?
The money for those items has to come from somewhere. Thats where your markup goes. If you just bill based on a few factors, eventually, you won't make money. you might make a few bucks on the first job or two, but eventually you have to replace things.
That long rant being said, I charge about 60 bucks a yard delivered and installed. The cheap customers balk...the good ones are happy.
By the time you can make ends meet....They move the ends.