OP, especially because you don't already have an ebay account, I don't think it's worth your time to try and sell these. And as others have mentioned, listing prices on ebay mean nothing if people aren't willing to pay that much. To put your mind at ease, however, it wouldn't take long with only 10 magazines to research if your specific issues are selling.
To refine what others are saying about researching listings on ebay, I actually suggest searching not by "sold items" but by "completed items." This search pulls up ALL completed listings, both sold and unsold. Then you can sort the results from low to high in price. That way you see how high you can price an item before buyers stop being interested. And you can see if, for example, there were 30 completed listings but only two sales, and let that tell you more about if an item is worth the trouble to try and sell.
You could also throw up an ad on Craigslist for the batch of the magazines, and see if you get any bites, if you want an ebay alternative.
Re. National Geographics magazines, the June 1985 "Afghan Girl" issue is traditionally the big seller among non-early (think 1800s) issues, but I think the markets' already peaked.