Last time I checked, flash memory was up to 100,000 write cycles. That's more than you'll ever use (unless some program uses it as virtual memory, or other similar snafu). I've heard recently about the advent of solid-state replacements for HDDs in the near future. That can't happen with 100,000 write cycles. They would not last long. I'm assuming it's flash tech, but maybe it's something else entirely.
More likely, your cheap SD card busted a gut, or got corrupted by static electricity. Sorry about that.