Amy's music, and other collectable items are obviously increasing in value since her death.
However, I would like to point out, to avoid allowing people to cash in on her death...
CD's on other sites, such as Amazon, are priced at around £4 for Frank, £3.99 for Back to Black, and £8 for Back to Black Deluxe edition, and various other lower prices with free P+P. These are prices for brand new and sealed CD albums. Don't pay too much!
Also, watch out for the framed gold and platinum discs, a lot have fake discs, printed using light scribe technology, and fake signatures, and are not genuine articles! These will not be worth ANYTHING. If you want to buy something such as this, then you need a genuine one (from Island records) if it is to hold any value. As a decorative item, however, the fake ones are fine, just don't pay through the nose for them!
Any genuine autographed items are worth buying, not just for the money value, but as a sentimental piece for any fan... Just make sure the autograph is genuine... Amy's was very easy to forge.
Once again, RIP Amy, and condolences to anybody feeling pain with her loss x