The Cancer Genome Atlas(TCGA) has open data for copy number variation(CNV) from at least 10k different cancer patients. They offer two types of data, CNV data from tumor and CNV data from normal tissue samples. Is there any other open databases that offer CNV data from at least one cancer type?
The ICGC has CNV data for many different cancer types. It has many both restricted and open data sets. The DCC releases page will let you hunt through them - those that are public are easily downloaded. They also have matched expression, SNV, DNA methylation, and structural mutation data for many samples.