I bought some cheap linoleum on sale. Works good for me covered with either wood chips, paper shreds, or leaves. I basically made a 12 inch deep well all along the coop walls to hold the deep bedding. In the back of the coop, I have a drop down panel so I can easily shovel or broom off the litter into a wheelbarrow or wagon.
Not only is free best, but I like to think it is my small way of being green by reusing stuff that would otherwise just go to a landfill. All my spent litter gets composted and used in my gardens.
My chickens don't go outside if there is snow on the ground. I built my coop almost twice the recommended 4 square feet per bird with the idea that my chickens would be living in the coop for about 6 months out of the year.
I know lots of people swear by Blackjack 57. However, I have also heard that Blackjack 57 can freeze and crack in our cold (-40F) weather. So I went with cheap linoleum instead. As far as cost, the linoleum I bought on sale was about $25.00 and I think the Blackjack 57 would have cost me about $50.
Yep, my chickens won't go outside in the snow unless I throw a layer of leaves on top of the snow for them. I usually do that this time of year when the days are warm but there is still snow on the ground. Unfortunately, we are in the middle of an April snow storm. It snowed yesterday, snowing today, and more snow in tomorrow's forecast. We expect to get about 5 inches of new snow. Oh well, at least April snow does not last very long.