Not a call but a text message from someone offering to buy an item I have posted on kijiji. Offering to pay using errand get and asking for my email address which is included in the listing. So there's really no need to ask for it. After being told I will only deal in person in cash and that I had seen scams from area code 720 numbers I got no further response.

Yep, the payment would have been bogus and you would have been out money.  Good thinking.

Just got a call.. Was suspicious but hopeful.. Wanted my kijiji item, said they'd pay 100 more for me to ship and send an etransfer.. I asked for bank, password and mailing address and got no reply.

Its a scam.  The buyer's payment will bounce, but not until after your payment to the shipper clears.  You'll be out $100.
Congratulations on not falling for it.