My recommendation as the forum owner would be to file a claim with PayPal immediately if you have been waiting longer than 3-4 weeks to receive your items and the seller is not communicating. Unless stated up front that there would be a delay, waiting this amount of time without regular updates is just unacceptable.
Unfortunately this would not be the first time that someone who we all think is on the up and up fails to follow through on sale transactions. The truth is, there are thousands of people filing through here each month and you're going to run into this sort of thing from time to time. Some folks like to talk a good game, but come up with excuses for everything. After 7 years of running this place I've found that even long standing members who were reputable in the past can still turn on folks and rip people off...just ask member Henry Morgan about member dumpster_diver from Georgia.
I'm an extremely busy person myself, and yet, if I sold some items to people and was unable to ship them immediately due to some unexpected circumstances I would move heaven and earth to make sure they knew about it and were updated regularly. If I knew it wasn't going to work out, I would refund everyone's money immediately and would gladly be willing to lose money in order to uphold my reputation...especially if I owned a business that I was promoting online.
As for the folks who donated parts to the auction bike project, I'm sorry to say that it looks like you are probably out of luck. From this point on members will not be allowed to start and forum supported project without first getting approval from the site owner.