There is no reliable information about the actual item quality/item levels right now.

However, with patch 1.0.3 the item levels for high-level items will be exposed in the game so you have a better possibility to directly compare two items with each other:

One problem we’ve seen -- and intend to correct quickly -- is players comparing high-level Magic (blue) items to lower-level Legendary items as “proof” of an imbalance. To help correct misconceptions of the actual stat budgets allocated to items, we’ll be exposing item levels (ilvl) of 60+ items in patch 1.0.3. Comparing an ilvl 63 blue to an ilvl 60 Legendary will hopefully make a bit more sense afterward.

(Source)

Additionally, the drop rates for high-level items will be modified with patch 1.0.3, so this could probably also affect items sold by vendors.

There is no reliable information about the actual item quality/item levels right now.

However, with patch 1.0.3 the item levels for high-level items will be exposed in the game in order to give have a better possibility to directly compare two items with each other:

One problem we’ve seen -- and intend to correct quickly -- is players comparing high-level Magic (blue) items to lower-level Legendary items as “proof” of an imbalance. To help correct misconceptions of the actual stat budgets allocated to items, we’ll be exposing item levels (ilvl) of 60+ items in patch 1.0.3. Comparing an ilvl 63 blue to an ilvl 60 Legendary will hopefully make a bit more sense afterward.

(Source)

Additionally, the drop rates for high-level items will be modified with patch 1.0.3, so this could probably also affect items sold by vendors.