I don't get assigned desktop appraisals because my fees are too high. Back a number of years ago I was talked into completing desktop appraisals for an AMC. They wanted to pay $35 per report, but I talked them into $50 per report at the time. In my head, an extra $100 per work day sounded like a good supplemental income, as the AMC said they had plenty available to keep me busy. In reality, it turned into a couple reports per week and after a few months I realized that they were cannibalizing my exterior driveby orders ($250 each at the time).
I don't know how much desktops pay now, but I get the occasional email from a new AMC stating that they are introducing a new desktop product and they'd like me to sign up for that same $35 per report. The problem even at $50-$75 per order is that you need to have a large steady volume of them to make any money. If I had a source for a few cookie-cutter type SFR per day, 5 days per week, I might even consider them again. If you had a steady supply, you'd be familiar with the product, submission process, and have all of your normal extra addenda able to be copied/pasted in to shorten the process. Without a steady daily supply, you're probably not familiar enough with the process to make a decent return on time invested per report.
The other factor with desktops and a high volume is the greater chance of something coming back to bite you in the butt. My normal fees for driveby appraisals now are equivalent to the fee for doing 8 or more desktops. So to make the same amount of money from desktops, I'd have to do 8 times the amount of desktops. In my opinion that's opening yourself up to a lot more potential liability.
One other thing, make sure you have an acceptable payment schedule in writing.....and hold them to it. A lot of times some new AMC will pitch it's desktop program to a larger lender in an attempt to replace AVM data. The new AMC gets a large volume at the beginning as the client tries them out. The new AMC thinks they're going to make huge money, but the lender drops them after 3 months. During that 3 months, the new AMC used most of the income from the client to recoup startup costs and pay direct employees, without any $ left to actually pay for the desktop appraisals they ordered. New AMC dissolves and you just wasted a bunch of time for no pay.