Can't Find Altera Max II EPM570T1005CN On Altera Online Store

There's plenty of these devices listed in Digikey's site for $13.30:

http://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&keywords=epm570t100

Note that you do not need the C5N, that just indicates the speed grade of the device. Since you have the project files for the design, you can change the speed grade and confirm the design meets timing. The "N" just means RoHS. If you happened to have some other version of these devices around, eg., C3, you could use them.

Cheers,

Dave