It's the wild west out there.
I've had two experiences. The first was while trying to sell a 30' travel trailer on sites such as rvtrader. Over a year I received dozens of emails such as one quoted above- the time pressure, unavailability in person, sending a "purchasing agent", buying a gift for a brother or other family member.
The red flags went up immediately- nobody buys a $20K RV sight unseen. Arrangements must be made for transport and license transfer, yet the buyer was always curiously unconcerned with these aspects of the transaction. AND- who sells an RV by Paypal?!
The worst tho, is that I have a handicapped sister who falls for internet scams all the time. Most of these are online-job type scenarios or contest wins which require shipping payments. She has sent close to $3000 in about 8 or 9 transactions over the past 3 years. I pull my hair out trying to convince her to always run these schemes past me before visiting the Western Union office but she is very independant. I'm in an awkward position of trying to guide someone who has the intellect of a child but is legally a competent adult.
I've spoken to Western Union and three different police departments, had statements filed and interviews conducted, but all the authorities ever do is provide sympathetic noises and issue safety lectures to my sister.
It's a terrible thing- that there are people out there without conscience who prey upon the vulnerabilities of others, but that's the nature of the times in which we live. I only hope that there's some sort of cosmic justice or karmic retribution for these criminals.