I think the scale-down answer in the $10 range is just an integrated cable otherwise for example the Mini and the Slim 5000 the cable can be comparable size to the powerbank.
Scale-up then the opposite as cable is the most probable to fail so having a built-in cable is bad. Scale-up you're talking $30-$80 powerbank.
I would say a Mini in the 3 popular flavors of one with lightning output, one with Micro outpout and one with USB-C output would sell well, with a flip-up type. These are purse emergency type situations just enough for a 1/2 - 1 full recharge for a long day or a bad app which unexpectedly drained phone.
I agree, wireless is a bad idea for portable chargers due to volume weight cost ineffiency consequences. Wireless for wired chargers to the wall is fine.