I rarely do this stuff, since I can't compete doing grunt labor with a guy paying $8/hour employees, but keep in mind that the materials do vary in cost depending on what you're putting out, so one fixed price isn't realistic for every situation. I put out 3 yds of bagged cypress blend in 3 hours, including cleanup, so I guess an hour/yd is a good time estimate, though I'm sure it could be done faster by a youngster. I think it worked out to $22/yd for materials, but the colored stuff was more. Add $50 or so for labor and that's $72/yd. Then you have to account for delivery time and/or costs. So it would also depend on how much you're putting out. A small quantity would need to cost more per/yd than a lot of the stuff. $75/yd sounds in the right ballpark, but I'd personally need to make more than that to want to do a lot of it, not being a fan of stoop labor. Also, putting mulch neatly into tight areas around lots of plantings is quite different than putting it in sparsely planted areas where you don't have to work around stuff as much. It's quicker to put out a deep layer of it than to try to spread it thin for a cheapskate customer. So factor that in too. It's cheaper I'm sure to buy it in bulk, but depending on the size of the job, the materials saving may not be worth the extra handling you have to do with it getting it into a wheelbarrow and then moving it from a big pile to where you need it. You'll also know exactly what you use with bags, vs. bulk. A "yard" at one supplier may be a lot more or less than at another (basically a "scoop" from a skid steer)
So, short answer..."it depends"