That's a good range. 
Market prices vary due to location, supply and demand, etc. A small town guy with super low overhead vs a photog in NYC or LA? Do you plan to spend hours editing, or just giving SOOC JPG? Do they get perpetual exclusive rights? Local, national or international distribution? Trade or consumer audience?
These kinds of pricing discussions come up from time to time and the above is, in my opinion, the only correct answer. If one can make a good living with a 500 dollar day rate by staying busy without much effort or overhead, I don't begrudge them charging what is a pittance in other markets. Likewise if one can change 2000 a day and work 5 days a month to cover expenses, good for them.
I am less interested in how many different sets they shoot than I am the time it takes to do it. I've stood around on location for an hour while a client gets their s*it together doing things they should have done in advance. I have also kept moving fast from set to set because things were organized. In the end it doesn't make that much difference, to me.
PSA: The above post may contain sarcasm, reply at your own risk | Not in gear database: Auto Sears 50mm 2.0 / 3x CL-360, Nikon SB-28, SunPak auto 322 D, Minolta 20