THe problem with escrow, though it seems like a good idea at first, is that it changes the who can get "Skroo'd." What if the person who bought claims they did not receive the item. Not all shipping methods provide tracking numbers.
Just a thought, though a good one, but the fees already from ebay abnd pay pal already amount to a lot, escrow just adds even more. Perhaps if it was offered to buyers as an ebay service!