With the revelation that Iron Patriot is, in some form, to appear in Iron Man 3, there suddenly appears to be a rush on the character's first appearances.
That would be Dark Avengers #1 of course, as well as subsequent issues of the series, with Norman Osborn in the suit. Not that he'll be in the suit in the film. Not that this matters right now.
It's currently fetching up to ten dollars on eBay but a lot of the is down to buyers hoovering up copies at cover price. Once they are all gone expect that going up sharpish, as well as subsequent issues.
Dark Avengers #1 was also available in a number of variants, including a blank sketch variant, making each one unique.
And right now Earth 2 #2 is on "backorder/out of stock" through Diamond Comic Distributors while one copy of the book has just sold on eBay for $6….