Well, maybe a chat with him, buying it on condition it passes testing for broken windings or shorts.
No moving parts in a stator, it's just poles with insulated wire wraps and what makes the juice is that rotor with a magnet passing the poles. You have the rotor in your bike.
I've bought a good number of items off the internet, off the phone before that, and knock on wood, never a bad dealing yet. Once in 2012, I agreed to buy 4 like new take off P275/55R20 Perelli Scorpions for my pickup from a guy in Kansas City, Mo. and I live in Va. Tires were some he pulled off his 2012 FX4, He said $200 plus shipping which was gonna be $157 for all 4. Then there was that trust issue. I told him via email that I'd send the $200 and he could send the tires and I could send shipping then. I started to write the check that night and decided what the hell, and made it for full amount. Funny thing was all 4 tires were on my carport two days later, he didn't even wait for the check.
Back in 1986, I saw a add in Car & Driver, a warehouse closing in NJ, full of Koni gas adjustable shocks it said. I called the phone number Monday afternoon, they had 4 to fit my '85 Thunderbird, they said I could send a check (was like $300 give or take). I wrote check and mailed on Tuesday morning. Wednesday evening as we were eating supper, UPS dropped my shocks off.
In 1994 I found a Triumph T150V MC in Vergenes, Vt. listed for sale in Old Bike Journal. I called the number on a Friday night, talked for awhile, agreed to purchase but explained I couldn't be there for a week or more as I only had one day off that following week. He said He'd hold it if I'd send him a $200 deposit. Deposit left here Saturday. On Monday, my Sgt. let me off work after court, wife and I left here at 11:00 AM in my '77 F-150. 760 miles later in the wee hours, I got a room in Burlington, Vt. At 6:20 AM on Tuesday I called the seller and he said he'd wait and go to his job late, gave me directions. I arrived, started bike, sounded great, said lets load it and we did after I backed my PU into a ditch. Come time to pay, he would only let me pay the agreed on price, less the $200 I said I sent but which had not arrived yet. I was a happy camper then. 760 miles home then.
Don't know how much is bein g asked for new in open box and open bag, but if it is new unused and if it's OEM I'd give it serious thought. Lots of reasons for open box or bag over last 20-30 years or more. My 1200's stator developed a problem on one leg in 1997, I put a new Honda "lifetime warrantied" stator in it, still going great. I recall there being talk of better insulation used with it? Seems then, over 20 years ago, was about $140.