term4sale.com
This site will compare all major term life insurance companies' rates. You can sort by company rating (basically, how likely they are to still be around in 20 years, in the event you were to need to make a claim) and by policy size and duration. It is especially helpful if you go through the advanced search and enter your health information. I have an extensive family cancer history, and only a few companies' underwriting algorithms do not take into account the types of cancer that my ancestors have, so my rates through those companies are dramatically lower than they would otherwise be. Had I just tried to buy insurance from a single "reputable company", it would have cost me more than twice as much for the same policy. When you have found the best/cheapest policy, it will link you to insurance brokers in your area who can sell you the policy.
Best of luck!