You are missing alot of information necessary to give you an accurate quote. Premiums are based on age, sex, smoking status, health and state of residence. State of residence is indirectly involved in that insurance products are available on a state by state basis.
For example, the best available non-smoker rates for a 50 year old male in Pennsylvania for a $300,000 20 year level term policy are $56 per month.
Be very careful when getting quotes. Often in an effort to close a sale an insurance salesman (or website) will quote a 20 year level term product that only has a 10 year premium guarantee, or they might quote you a rating class (preferred best, preferred, etc...) that they know you have little chance of qualifying for in an effort to appear cheaper than their competition.
Find a financial planner in your area that specializes in insurances to help you. Avoid captive life insurance salespeople and run away from anyone uses a "multiple of salary" approach to determining your need for coverage. If you happen to be in the greater Philadelphia area, let me know.
UPDATE:
Actually the top five companies that I deal with all came up at $56 -$58 per month. Check into First Colony, Reliastar(ING), Banner, American General or Lincoln. Remember, the premium rates I mentioned represent the best possible underwriting class from these companies. You will need to pass health underwriting with flying colors to qualify.
Hey, do what you can to keep the Pens in the Burgh. Let me know if you need any further help with this.{the insurance, that is} I am licensed in PA.