I have to say I'm on board with blue90292 and shandea here. When it comes to our dogs, cats, parrots, and small animals vet costs are naturally figured into their care. One of our parrots is valued well over $3000, so an investment of $200 or more to save her life would be worth it IMO. Plus, she is a part of the family.
I look at the chickens for what they are. Chickens. I do love the little boogers, but they are just chickens. I can not rationalize taking a chicken to the vet when the chicken cost barely $2, just as I wouldnt take my son's hermit crab to the vet for the same reason.
I understand I am about to be booed here for saying this, but we all need to keep in mind WHY we raise chickens. We shouldn't be raising them as PETS. Chickens are meant for two things (unless you show them) eggs, or meat. Just the same as a cow, or pig. I consider myself a farmer. If you asked a farmer to take his sick cow to the vet he would laugh you out of town and tell you his sick cow is tomorrow's hamburgers. UNLESS he thought it may be something seriously contagious that could infect his herd, and thus his livelihood.
I understand that some of you dearly love your pet chickens. But in my eyes, chickens are chickens. I have some now that I am quite fond of, but if something was seriously wrong with one and there was nothing I could do, rather than let it suffer I would end its pain. Would it bother me? Of course it would. 
But we AS FARMERS, which we ALL are once we take upon raising LIVESTOCK, need to remember why we chose to raise these critters in the first place. If you raise them simply to look at and talk to and do not benefit from eating the eggs they give you, then you could technically consider them a "pet" and care for them like any other pet you might have. However, IMO if you are eating their eggs (or their meat) then you are raising them for THAT purpose, and they should be looked at as such.
Of course, this will be one of those topics that will get 100 posts because each of us will feel differently. Thats alright too. Everyone also has their strong emotioned opinions about things like politics and abortion. Its normal. Personally (and strike me down for saying it if you must) no matter how attached I become to these critters, in our home and eyes they will always be seen for what they are.....just chickens. Thats just MY 2 cents.