Ellis has a lot of them, and they also seem to let shoppers with good track records auto-assign shops (not necessarily video ones, but either unrecorded or audio) right away. I am not familiar with how quickly they pay out, however, or whether or not they are difficult to work with.
I suppose it depends on your geographic area, but especially if you can shop an urban area and/or have your own transportation, you could likely do several video shops per week and make pretty good money. MSCs will sometimes also loan equipment to the right shoppers, though priority in assigning video shops does tend go to shoppers with their own equipment.
Depending on which equipment you get, which jobs you land, and how many you can land, you could probably make the cost back pretty quickly. You may also need to invest in certain kinds of clothing if you don't have it already, though---MSCs which schedule the video shops tend to want you to wear professional clothing with button-down shirts or jackets, and you'll probably have to make some minor alterations in order to conceal the equipment. Of course, if you have your OWN video and audio recording equipment which is more easily concealed than what some MSCs are willing to provide, then you might not have to do that. Pretty sure the more discreet equipment tends to be more expensive, though, unless you're able to make it yourself.