whats the trade in value for an imac?

Not sure where you are located, but in the US, most Best Buy stores

also have a Trade-in for gift card program.

As far as selling, unless it is only a couple years old, it will be a hard sell.

Back when I got my 2013 iMac I had an early 2009 iMac I wanted to sell

and an even older MacBook (second gen Intel model). Put both on

Craigslist. The MacBook sold the next day but after a month had no

inquiries about the iMac, other than the scam artists "send it and I will

give you money when I get it" types.

Also, anyone with half smarts are going to want to see it working. So

you will need to be prepared to cart it all somewhere or have strangers come to

your home.

I sold a 27" iMac via craigslist - meetup was set up at a Safeway grocery cafe area. Plugged in the iMac and the buyer was able to test and happy to give me cash. Right next to the cafe was a small branch of my bank where I immediately deposited the money so there was no worry walking back to the car. Worked out well.

You'll need to fill out the info here in order to get an amount. Please note that you will invariably get more by selling it yourself.

Renew and Recycling - Apple