I'm sorry it took me so long to get back to everyone on my interaction with Derek.
I contacted him regarding some Exo Terra cages he had advertised amongst other things (including geckos) on Craigslist. I eventually suspected it was Derek, since Barre is a very small town and not many people keep geckos in MA. I did not get an email back, and because Derek probably knew my cell phone number, I asked my girlfriend to text him about the cages. At the time, I was in contact with another member here on the forum, and promised that I would do my best to discuss with him the possibility of relinquishing at least some of the geckos that were bought by single individuals.
He replied via text and seemed very anxious to sell the terrariums. We went back and forth with offers, and he declined my highest bid so we did not text him back immediately. He then rescinded, saying that he'd go lower - we agreed on $80 for the three terrariums and hoods. On Friday, 4/1/12, we scheduled a rough meeting time for 8pm. I ended up having to do some thesis work, and was running a bit late. In the meantime, he texted my girlfriend that he could meet in Worcester, then asked for an additional sum of money. We declined, and said that Worcester would be better for us (cutting off an hour of the drive), but were not interested in paying more money. He got irritated slightly, but we were able to follow through with the transaction.
We (my girlfriend, my friend, and I) got to Barre I believe around 9pm or so (it may have been later?). Upon arriving at his house, someone from the upstairs window was looking out and smiling and waving, but did not come downstairs and just watched us - kind of an eerie feel. Derek came out with the tanks, and my girlfriend gave him the $80 a bit preemptively. I asked him about the hoods, and he said that he would only do the tanks for $80, but would give us the hoods if we gave him another $20. I told him that we had agreed on a set price for both the terrariums and hoods, and drove 2 hours out to Barre even after the false promise of being able to meet him halfway in Worcester. I stated that if he didn't include the hoods, then I wasn't interested in the terrariums and to give me my money back. He stared at me for a minute, and to be honest, I'm not easily threatened, but there was something about his attitude that suggested he could turn violent and that he might be under the influence. His response escalated in anger quickly for no reason - no honest and sober person would react the way he did - and he eventually ran back into the house and locked the door. We stood for a while in the driveway, and eventually he came out and threw the hoods at me while shouting profanities and telling us to get off the property before he called the cops.
Shaken up, we decided to go to the local police department and file a report after recouping. Cpl. Ury was actually on duty, and my friend and I had the pleasure of meeting him. We reported the incident, and I presume that law enforcement went over to his residence since we got a text (I believe the following day) from Derek calling us "morons", saying we stole the terrariums, stating he had the license plate number of my vehicle, and that he was going to file a report on us.
From what I understand, he seems to be well known by the police in Barre for smaller incidents. Although I didn't lose any money or assets in the transaction directly, I can still provide my own encounter as a witness to his behavior (and the two other people from MA that I was with can do the same). Attached are screen shots of his Craigslist ad, which is still currently active on the site.