I've used Craigslist to sell dozens of household items over the years, and I've noticed the larger-priced electronics are frequently targeted by scammers. They'll start the conversation sounding enthusiastic and very interested... and then they'll suggest an overly generous offer that will compensate you for shipping the item to an undisclosed location.
Here's a recent example from a laptop I'm trying to sell on Craigslist:
1. Caller has a non-local area code. Not everyone who calls from a non-local area code is a scammer, but every scam I've received has been from a non-local area code... so it should at least be a warning flag.
2. The message is written with an overly enthusiastic tone. Legitimate buyers typically try to mask their excitement about the item you're selling, because they know they lose bargaining power if you know they badly want the item.
3. The buyer makes up a story about being out of town or not being able to pick it up in person, and is willing to "make it worth your while" by paying extra and in advance.
The old saying "if it sounds too good to be true, it probably is" holds true in 100% of the time in these cases.
It does you no good (in my opinion) to try to confront the person or get them to admit they're scamming you. You can report them to craigslist or the authorities if you have the time/energy, but I prefer to just end the conversation and block them from contacting me in the future.
To block a caller, tap the "Details" link at the top right of the IM conversation. This will open the contact details page.
Next, tap the information icon at the top right.
Tap "Block this caller" and confirm that you want to block the caller, and they won't be able to contact you in the future.
Remember, legitimate buyers will meet you in person and never pay in advance for something they haven't seen or verified that it even works.