It would really depend on what your monthly needs are. I generally earn more than $1100 per month and that is not unusual for shoppers who have figured out where the shops are and are actively doing it. But that is usually fees + reimbursements so would do me little good if my mortgage was $1000 per month.
I know a shopper who drives routes through the state who earns significantly more than I do, mostly fees and is substantially supporting his family. I gather he is mostly doing the same 2-3 jobs at location after location as he goes through rural and outlying areas that are hard to fill.
One shopper here mentioned recently that between himself and his wife they target doing 100 shops per week, I do only 60-70 per month.
I have no intention of setting up routes that require several hundred miles several days per week or even per month. There is a law of diminishing returns. I take the jobs locally that the fee is worthwhile, the reimbursement is useful to me and the combination of fee plus reimbursement is not insultingly low for what is expected. If I left it at that, I would be doing about 40 jobs and earning about $800 in fees plus reimbursements ($20 average shop). But my monthly goal is $1100 and getting that last $300 is likely to take 20-30 more jobs ($10-15 average shops). If I took everything I saw, I could earn a few hundred more bucks, but at what cost? If I liked McDonalds hamburgers I could do a whole lot more jobs. But I don't, so the reimbursements for their junk food is of no use to me. Thus to me, those jobs are worth only the fee and thus are worth only the $7.50 fee for about an hour total of my time. I could grab up a bunch of gas stations paying $4 with a $1 gas reimbursement and a $1 inside purchase. The inside purchase in my situation is a waste of money and buying gas $1 at a time is silly, but at least in theory these shops are potentially worth $5 to me--20 of them needed to make $100. So generally I draw the line at $15 that a shop needs to pay in fees and/or useful-to-me reimbursements. At that, my market supports me for around $1100 per month, with generally about half of that being cash. I shop the 4 communities that are in close proximity and beyond that expect mileage and higher fees when asked to help schedulers get more distant shops filled.