I used to do good on ebay then they got to lax and had lots of scum playing on there. Seems like it has been getting better again. Hardest thing is to find products that will sell for enough to cover all costs including product cost, listing fees, paypal fees, final sell fee, etc.
$80K is like minimum wage in some areas. Consider housing costs. $80,000 home my area would be around $1,000,000 in San Fran. I have met many people that actually sold their homes in Cali or NY and moved to our area bought or built nicer homes and still had money left over to retire on.