A great source for price comparing also is
http://www.toolseeker.com
They will list the cheapest place selling the tool you want and even keep up to date on discounts being offered to include the codes to get the discount.
I have the Porter Cable 4" and it rocks!
I would be hesitant to buy my tools off of Ebay "WHITHOUT" being able to actually inpsect them. I have driven a few miles to look at some stuff on Ebay and in most cases its fine but a had a couple times where I was very pleased I drove the 60 miles. It kept the money in my pocket and my blood pressure down.

Some people just have no decency and make an effort to circumvent the system to present themselves as excellant sellers.
Vermont Lumber Liquidators comes to mind. That guy ripped off lots of folks and then filed bankrupcy, yet his profile reflected nothing but awesome reviews......................from several of his family members that were in the scam with him.