The best thing is get rid of the stupid fee split system and eliminate bidding.
The idea of appraisers charging for bids makes sense but most appraisers would be too scared to try it. However, they could try it and put the AMC;s on the back foot for a change. Charge $10 -$25 per bid, payable by credit card. ( as the AMC makes the appraiser pay a portal charge of $10-$25 to submit an appraisal report. )
If an appraiser wins the bid and gets the order, they can deduct the bid charge from the fee.
I put it out there more as a hypothetical - it costs the appraiser time to research a property and respond to a fee bid request - and their own bid is used against them by the AMC to find a cheaper appraiser. Thus, the bids have value to the AMC, yet they are getting them for free.