How can I find old Dungeon and Dragon magazine articles without a subscription?

I have an interest in the pre-WOTC editions of Dungeons & Dragons, and would like to learn more about the history and foundation of the game; I would therefore like to get a hold of various back editions of Dungeon and Dragon magazine.

I’m aware that a D&D Insider subscription comes with access to the magazines. However, I’m not enthused about paying for a continuous subscription to maintain access. I’d rather pay once, and I’m not interested in the more recent WOTC products.

Is there any legal and reliable way I can get access to the old editions of Dungeon and Dragon magazines without having to pay over time to maintain that access?