I don't think you "blew it" by not doing things that way again. $75 is way too little for the effort you put into it. Have you booked any private sessions based on the in store work? If so, we're those sessions good sellers?
There will always be someone willing to do it for next to nothing, but of you want to do this as a business that someone can't be you.
Sounds like it is time for you to start marketing in other ways.
BTW, nothing wrong with working with the local Humane Society, it the national HSUS that is an issue.