There is publicly-available 450K data in The Cancer Genome Atlas (TCGA).

It's a little difficult to navigate for new users. I would start with the data matrix and select, for example COAD (colon adenocarcinoma), then DNA Methylation under Data Type. You should then see JHU_USC HumanMethylation450 under Center/Platform.

There's also direct FTP access; here's the COAD 450K directory.

You'll need to spend some time reading the TCGA documentation to figure out their barcode system.

As of today, it appears that 2215 samples have been assayed on the illumina 450k platform at NCBI GEO.