They shouldnt ask you for a salary, its not very ethical. For exemple, what would happen if you ask let say 30k then after a month you realize that all your coworker are getting 55k ?

I think you should return them the question by asking them about their salary grid and progression. You should never have to give a number. If they dont have any, ask them about how they evaluate how much people should get. They will feel the trap and will switch subject. If they say that they pay according to number of years of experience then you just tell them that since you are just starting its going to be easy to know how much thry are willing to pay you.

Also, we need more infos: do you want that job much? Do you HAVE to get a job or you have something right now and you can look for other openings? Your negociation power depends of a lot of things, but one thing that I learned is that salary is the least concern when hiring someone, unless the company has some financial problem but in that case you dont really want to work there anyways.

Actually, salary should be only talked about once you have passed the first few rounds of interview and you are almost sure to have the job, its supposed to be a formality, not a problematic subject.

The best salary sources are schools. Give them a call and ask them the average wage of the last graduates. The 40k$ figure seems a little high to me but I am living in Montréal were life is cheap...

Anyways, all this to say that salary wont be the reason that they refuse to hire you, at least not if your skill justify it and of course, that you are not asking for a ridiculous amount. Just make sure to show them what you can do for them and how creative/productive you can be!

Good luck!