We decided on the end date: the last Friday of April (the 30th).
I updated the first post with these details:
-- The winner will be drawn from all posts in the forum from March 15th to April 30th. Meaning: more active members will have better odds.
-- If the winner chooses the $150 Aveo parts prize, they'll receive a credit to the vendor of their choice (from our list of vendors).
We've been in touch with a handful so far, and have had a positive response from a couple - still waiting to hear back from the others.
More details about vendors to come in the next week or so.