I can see what you mean about the amount of money people would be willing to spend on care for an animal that is already sick. Obviously someone is going to be quicker to pay for a $1000 treatment for a $10,000 animal than they would be for a $20 animal but I feel that has more to do with caring about the money that you've spent than it does caring more for an expensive animal.
At the same time there are many expensive animals that suffer neglect and abuse. I have seen neglected horses, which are relatively expensive animals. There is a zoo in my area that has poorly cared for jungle cats and even elephants. On the other hand I know people that have spent hundreds of dollars treating a cat that they got for free. A friend of mine had an iguana that he paid about $30 for that he regularly took to a vet and spent all the necessary time and money to keep it in excellent condition and it lived a long time.
Another thing to consider is the ability of those keeping the cheaper animals to pay for any necessary medical care. Chances are if you can only afford to keep a $20 snake you can't afford to pay hundreds of dollars to a vet if something goes wrong. If you've shelled out $10,000 for a high end snake then it's likely that you have the disposable income to pay the vet if needed too.
All the vet bill stuff aside though I don't think that the price someone pays for their animal will tell you how much care and attention they will give it. In fact those who can only afford one, low priced herp will likely fuss over the $20 animal way more than the guy with the same animal as part of a big expensive collection.
I feel a little light headed... maybe you should drive...