
Short answer: ignore them.
Long answer:
I'm thinking it's ridiculous for a buyer to give feedback first; realistically, the seller gets paid first, they should give their feedback first. A buyer should give their's only after they receive the item and have checked it out, and/or settled any differences with the seller. The ebay/PAyPal dispute system will use positive feedback you leave against you - don't gush prematurely unless it was an "as is" item.