Do you guys have any whip suggestions? What do I need to be cautious about? I see some on eBay for like $10... other sites for $20 to $40. Are they all interchangeable? I have a VaporBrothers but I've heard the Silver Surfer whip is the best. Do they both fit the same? I read that on the VB the heating element is 16mm and on the Silver Surfer it's 18mm... so I'm a little concerned about that. I just don't wanna pay so much for VB's kinda crappy whip...