If I were in your shoes, I wouldn’t be buying anything at all. You sound like someone who wants to buy a piece of OA because you feel like you should have a piece of OA. Frankly, I don’t think that’s a great reason. A lot of pricing is a function of nostalgia, so if you don’t feel for the piece, what’s the point?
I’m unusual in that my taste hasn’t wavered much over the years; it has grown more expansive, however, as to what I consider good. My first 3 purchases were a Neal Adams Phantom Stranger cover, a Swamp Thing page from the Tottleben/Bissette run, and a title page from a Spirit weekly (since destroyed by flooding). I knew what I liked, and what I thought was good. It hasn’t changed.
Coollines does sell, you know, but they are high. You might be better off waiting until something comes up at an auction sale in the next 18 months or so, and use the time to study the market. Nostalgic Investments isn’t as bad, but Bechara knows how to hold onto pieces and extract a high price for them, too.
And yes, things do go down, but quietly. Golden Age work, so I hear, has dropped. So have some specific artists. Sometimes, rather than acknowledging a drop, a piece will sit in a dealer’s inventory for a long time, and it then shows up in auction. That’s how I got an 8 page story from Cool Lines. There has also been a lot of speculation on the boards about when/if the bubble will burst. But, if you love the piece, it never really will drop because price is irrelevant.