Vintage Life Magazine Values

Can anyone tell me the value of my vintage magazines?
I currently found some old magazines at the antique store in town and thought they were cool. After looking on the web and doing some research have found some prices but they have a very wide range. If anyone could tell me an acurate price on one of the following magazines, please answer.
September 19, 1936 Radio Guide
October 14, 1933 Collier’s The National Weekly
July 1948 McCall’s
November 18, 1966 Life (Robert Kennedy will Run)
This last one was said to be worth at least $60, is that true. If anyone can help please do.
I have some vintage mags also and I am currently researching the values of them.
So far I found this website: http://www.dtmagazine.com/ which has a detailed price list of the magazines I am researching. I’m not sure if it’s legitimate or not but you may want to check there. Also you can contact Antique Road Show appraisers. http://www.pbs.org/wgbh/pages/roadshow/series/appraisers/index.html
Have you tried searching Ebay to see if your specific item is for sale there.
Good luck,
Jeff S
Thrift finds: Summer tops & Vintage LIFE magazines