All the individual DLC packs are being listed as Free on PSN.
http://imageshack.us/a/img842/5728/1000383a.jpg
http://imageshack.us/a/img39/5903/1000384r.jpg
http://imageshack.us/a/img600/7371/1000385s.jpg
http://imageshack.us/a/img29/9620/1000386nq.jpg
But I already have them all purchased so I'm not sure that I have a way to verify this myself since I already had access to them and I already have them all downloaded. Someone else check PSN and verify if you can really download these DLC packs for free.
INB4 "They're "Free" because you already own them": Uhh... no. Things you purchased show up as "Purchased", which you can see in the first pic for the Zack Island stage DLC.
http://imageshack.us/a/img842/5728/1000383a.jpg
http://imageshack.us/a/img39/5903/1000384r.jpg
http://imageshack.us/a/img600/7371/1000385s.jpg
http://imageshack.us/a/img29/9620/1000386nq.jpg
But I already have them all purchased so I'm not sure that I have a way to verify this myself since I already had access to them and I already have them all downloaded. Someone else check PSN and verify if you can really download these DLC packs for free.
INB4 "They're "Free" because you already own them": Uhh... no. Things you purchased show up as "Purchased", which you can see in the first pic for the Zack Island stage DLC.