Is it rude to ask for salary range?
If you are only willing to take the job if it meets specific salary requirements, say so up front. If a company contacts you to set up an interview, be direct but polite. If they ask what you're looking for in salary, be honest.
How do you say your salary is low?
If you can't reach an acceptable salary figure, and you don't feel that associated perks and benefits add enough value to the compensation package to balance the low earnings, respectfully decline the job. Thank you very much for the consideration, and the offer, but I'm afraid I'm unable to accept the salary.