Updating my Garmin 2720 maps...?

I just purchased a used 2720 to replace my 2610 as I thought with the NT map system I could still update it. I just found out that Garmin no longer supports map upgrades for my new to me 2720

I went with the older Garmin as its a good unit, good price and I have 4 bikes set up to us it (ie: one mount and 4 power cords hard wired into bikes) so I didn't want to have to re-work all 4 bikes.

Can I still find a copy of the DVD called:

Garmin City Navigator North America and Mexico NT DVD 2013?

Apparently that's the last one available for my GPS.

Or are there other options (ie: free maps)?

Thanks in advance for your assistance!