As far as Stein Air not doing this avionics go-between thing, they don't have time. Business is good for them and experimental panels is now just part of their "business model".
As far as the details of what happened with Stein's wire transfer don't know, but for the record a bank wire transfer is usually very secure, a done deal once funds are posted. It typically cost about $25 for the sender or funds and takes one day at most.
I bought $2000 worth of stuff VAF classifieds. My credit union security called me, asked me do I know this person. Also wanted to know what PMAGS were. Well PMAG is also brand magazines for firearms. That was a red flag. I assured them all was well. They also informed me this is like sending CASH. Once money was transferred it was gone. I talked to the Gentleman on the phone before we closed the deal. He had been a long time member, but somewhat inactive. His phone number area code did not match his state. He retired and moved to be close to grandkids. I was comfortable but it was something I needed to make sure about. I also called Brad at PMAG about the serial number and etc... STILL there is always a risk when doing on line private sales not on credit cards (which has quite a bit of protection).
I have bought several things off of VAF Classifieds from $60 to $2000, many purchases in $100-$400 range. Never had an issue, and seller packed and shipped expeditiously and item was as advertised. Great deals.
EBAY - I have never had any problems on eBay and been on there for 14 yrs? Minor hiccups as a seller and buyer, but got many good deals and sold a lot of stuff I no longer needed or wanted. I will say as a SELLER if your buyer is a flake eBay is full biased against sellers and pro buyers. That is great as a buyer. I have never lost money. Seller Fees is another thing, but it's a great way to sell things.
I have SEEN FRAUD on eBay and reported them. +10 yrs ago saw fake ads for in panel IFR Garmin GPS (e.g., 430), very good price, too good. The seller was located Eastern Europe and wanted Western Union. eBay has shut that scam down, as you can (or should) only use in system payment (ebay or paypal). There are strict rules about sellers/buyers contacting each other outside of their message system and giving personal info. You only get real name and address buyer or seller after a sale is made.
Facebook market place is wild west of on-line selling. 90% is pretty straight forward, shenanigan's are pretty common. Most are pretty obvious. Common "MO" is posting something for sale. I get immediate response they want to buy it (asking no questions). They usually "phishing" for info, address, phone number. I see their profile has just been created, no profile, friends. They typically post a picture of a woman or family, but no profile. I report them and block the account. I can only assume they want IDENITY to sell or commit further fraud / theft or are just trolls.
Fake accounts - The scammers can hack into real account like has happened on VAF Classifieds and Facebook marketplace. Despite Facebook being annoying with people inquiring, is great for selling locally but scammers are all over but pretty obvious. As long as you don't give out personal info, meet in public place, and take cash only. There is the risk however. A few in the news cases of people being robbed or worse from Craigslist and Facebook meetings gone wrong.
Specialty sites dedicated to specific items, like luxury waches. They charged me 6.5% to sell and buyer had to pay TAX.. Ouch. However you get payment escrow, shipping, and guarantee for the buyer it's as described. If there is an issue they do the abirritation. As a seller you are usually liable to accept a return for the least of complaints.
However if dealing with pilots and fellow EAB builders it is pretty safe, as the aviation community is safe. However that TRUST makes us vulnerable if we don't use due diligence.
Venmo or Zelle. Not sure what the scam is, but people will insist to use this payment method. It may be innocent. They also may get some commission for signing you up. Once you do they back down (I am guessing). They do have one big advantage send money for no cost. Paypal chargers 2/9% for a sale of item, but they are also no fee sending money to friends and family. However PayPal has protection for sales not the latter.
Venmo and Zelle both want your BANK ACCOUNT AND PASSWORD.IF ANYONE WANTS YOUR PASSWORD NOPE.... Venmo is owned by PayPal so... The great thing about the alternative pay services is they do not charge a fee even for sale, but no protection like PayPal. I do have a receive only account with one of these, using a debt card. I do not give my financial institution info/password. I can't send money only receive.
BOTTOM LINE it is a mutual trust thing between seller and buyer. If is ANYTHING does not look right walk away or click away. The more I sell on line the more I meet scammers on line. That is all they do is pose as buyers. What their scam is I don't know but they all seem to follow some MO they learned online. Of course I just talked to a Nigeran Prince who needs my help to get money out of the country and will pay me a large commission. Ha ha
"IT IS NOT PARANOIA IF THEY REALLY ARE TRYING TO GET YOU"
"IF IT SEEMS TOO GOOD TO BE TRUE, IT PROBABLY IS"