For those who like fashion, you can purchase new outfits for 300 or 1000 gold . Their only purpose is to change the look of survivors. Once you have bought one, all your characters can wear it. You need to go on the character you want and click on "change outfit" then click on the outfit to wear it. Click again to change back to your default outfit.
There was a 50% off sale around Christmas 2015.
One outfit was given for free in 1.5 update. It was Andrea season one outfit, if you had none.
Version 1.5 and below outfits cost was 1000 or 2000 gold, this has been reduced to 300 and 1000 gold in updates 1.6