This is the paypal scam in a nutshell: the scammer is trying to get you to send them money via western union. That's it!
The seller thinks they are getting top dollar for their item for just a little bit of trouble. All they have to do is western union money to a "shipping agent" and bam, paypal releases the full amount of the cost of the item, reimbursement for the shipping costs and maybe a little extra for their troubles to their paypal account. Hey, they even got a "legitimate" email from paypal telling them this, right? about how safe and 100% secure it is?
Can't you just hear the scammer/"shipping agent" laughing all the way to the bank with the 450-850$ you just sent them free and clear with no way to trace?
Had my car up for sale on a classified ads website. Got an email from 'Kathy White' saying she wanted to buy the car for her cousin as a surprise. She was conveniently away on business therefore could not come to view the car, but was happy to pay the full amount that was advertised and she would send a shipping agent to pick the car up. 'She' only wanted to deal through PayPal, and became quite pushy in trying to get my account details. I told her cash only and I've never heard back. Definite scam.
Same thing as everyone else. Have a wedding ring for sale and got an email asking if it was still available, left the phone number. Not recognizing the area code I looked it up right away and saw it was a scam. I've had others contact me as well and push for the paypal info like people have said. So I'm sure if I responded she'd have asked for the same thing.