I think a big part of this problem is that folks don't realize that bearded dragons can't live off the same sort of money that you would need for a dog or a cat. They are not low maintenance animals. With a dog or cat or even some birds, you pay a nice sum of money at first, then care is relatively inexpensive after that unless serious health problems occur. You can buy huge bags of dog, cat and bird food relatively cheap and you don't have to worry about keeping your bags of food alive, gutloading, adding extra nutrients etc.
I feel pet stores are a big factor in this issue. An average person does not research things online or on forums like these before buying a new pet. They trust the pet stores and their employees to provide them with accurate information and caresheets. I do a lot of shoppng in pet stores and not once have I even been told what the costs would be, nor do I hear them tell any other customers that. When you buy an expensive car, you expect to pay premium maintenance costs. Bearded dragons themselves are pretty cheap to buy, so the normal shopper will have no idea what the actual costs for maintenance and vet visits will be.
I started with one beardie, made sure I could take care of it and did some serious thinking about the cost for feeding, lights and care beyond the initial start-up costs before I took in any more rescues. I bought used cages and made sure I could raise enough feeders on my own to offset vet costs and and use my skills from many years of laboratory work to do my own fecal screens. I do think herp vets charge ridicuous amounts of money for the same services they provide to dogs and cats but I think that is because they know other vets won't work with herps and they can charge a premium. I paid over $70 for just an in house fecal from one vet and it actually made me mad because they quoted me $39 over the phone.
I don't flame anyone for saying they can't afford a vet because you don't know what their circumstances are and herp vets are indeed more expensive than you would expect. I do dislike posts from folks saying they are too broke to feed their beardies, then they argue about keeping feeders or raising their own, and then later you see they are looking to get even more pets. That makes me crazy!