Chuck, you'll get as many answers as reponders to what to charge.
A lot is based on where you are and how many other people are out there competing for the same thing.
I've not maximied on it yet, but here, landscape companies and contractors charge a huge amount, and generally aren't into small jobs. I'm trying to get those, but even with decent advertising, I've not gotten enough biz to keep going so far. I'm retired and part time, so I can handle it for awhile.
For example, just prior to me starting, I was asked about bidding a backfill around a foundation job, and doing some grade work. At that point, I was not experinced in pricing, and figured (did not bid) it would be a $500 job. With what I know now, I would bid $1000 or so.
The best bid they got and finally accepted was $2,000.
That told me I was too cheap.
Currently waiting for the weather to thaw, and I'm bidding to redo a community park area playground, replacing the sand, putting down new liners, and new landscape timber.
I figure two prices, what I think it will cost me and what I think a "real" contractor would bid. I go about double what I think it will cost me, then add a few hundred for risk, and generally is less than what I think a real guy would bid. I give the customer a firm, fixed price for the whole job.
I knew going in I didn't want to do work and not make money, even though my first few jobs I horribly underbid! Now if I get a job, great. If the customer thinks I am too high, he can rent/buy his own stuff and provide his own labor. I've not lost many jobs I've bid on yet........
Hope this helps.
ron