Scam.
The way it works:
He pays for the item + extra fund to cover his shipping agent with a bank draft or cashiers check.
He sends you a check, tells you to cash it and send the extra money to his shipping agent via wire transfer or prepaid card.
You cash/deposit check and wire/prepaid the funds to the agent.
Later, the check bounces as it was counterfeit. The money you sent to the agent, who is really the scammer, is unrecoverable due to it being wire transferred/prepaid card.
You are out money and now run the risk of being arrested for passing a counterfeit check.
See:
http://www.fraudaid.com/
http://www.fraudaid.com/solution_center/solution/draftsoption1/2a.htm

For transactions through PayPal, what they do is send you a fake PayPal deposit notice email, spoofing the official PayPal notice, that says the money has been put into your account.
You, thinking PayPal has your money, go ahead with the wire/prepaid transfer to the shipping agent, who is really the scammer.
After that, you then find out there was no money transferred to PayPal and are out the money your wired.

This doracharity01@gmail.com also emailed me saying she is interested to buy my phone i posted for sale online. She even gave an address where i should send the item. she even offered to add an x amount for the shipping cost on top of my asking price. i was hesitant thinking its a scam and just told her that my phone is locked only in my country.

I got the same persons contacted me. A doracharity01@gmail.com emailed me and offered to buy my HTC phone. She said she'll only transact and make payments thru PayPal. What did you do?

Got a text from this number- scam
Wanted me to send them my galaxy Tablet I had for sale on Craigslist. Watch out!!!

Its 90% likely a scam.
please dont involve yourself in any way.

A lady named Dora and her husband Mike who is apparently stationed in Africa wants me to send my iMac I'm selling abroad to him. She even gave me a phone number to call him and confirm (+27744732972) I haven't called him yet.