Vet cost?

Question
I have a 2 year old rat called Hannelore.
Shes very aggressive (Always bites in a frenzy drawing alot of blood), so I've never been able to handle her but I love her all the same. Over the last few months shes been putting in a large amount of weight and her fur has lost its shine, she isn't even cleaning herself anymore. Just this past week shes started to wheeze, it sounds like theres a marble rolling around, but once I go over and tap on her cage she stops and runs to the bars like normal.

I don't know what to do. I'm looking into taking her to the vet but I don't think I'm going to have enough money and my mum just says 'put it down yourself' but I can't bring myself to do it.
How much does it roughly cost to have a vet look at her?  

Answer
eek, I'm sorry to hear about Hannelore.

I don't know what prices run in Australia; here in the states the basic vet visit will cost you anywhere from $50 to $100 for an examination and euthanasia runs from $15 to $50. Of course, the more they do, offer, give, etc. will change the price.

The wheezing you're hearing may likely be a respiratory infection, which is relatively easy to treat if you can catch it in time. The gaining weight, however; is indicative of some sort of internal issue. Sometimes it isn't weight, but a tumor, or pregnancy, or another equally as unexpected condition. A vet check before euthanasia is always the best thing; but if she's aggressive, it may not be that easy.

Good luck.