Hey, I hear your frustration on the classified rules but you're right, it's due to potential scammers. That, and we want people to contribute to the forum and that's also part of the reason for the 100 posts. As far as buying parts, you can always browse the ads and respond by PM, that's usually more effective, anyway.
IMO, selling a car on here is a little difficult anyway; you have a relatively small audience compared to, say, Craigslist.
All that said, I'll take your feedback to the staff, but to be honest I don't see the rules changing anytime soon. I hope you stick around, log some posts and good luck selling your car.