Great News ! All the SimCity versions available on GoG are on sale until May 14th.
Simcity 2000 - $1.49
Simcity 3000 Unlimited - $2.49
Simcity 4 Deluxe - $4.99
You can buy the series (all 3) for $8.97
If you don't already have the digital versions, now is your chance to get them cheap.