Well I found a spawner on my wild adventuring and I would like to make a grinder for it but would like to build it in SP first anyone got a seed with a zombie spawner near the spawn? P.S. I tried the Minecraft Seed Website but couldn't find any.
You could use World Downloader. It will save the area around your spawner into a map you can then load into Single Player: http://empireminecraft.com/threads/mod-request-world-downloader.18294/