You get what you pay for.... The actual chips inside these things are made by a very small number of companies... the best ones get sold off at the highest price to the big name brands, the ones that have quality control issues are rated and categorized and sold in bulk to discount brands. So a bargain basement priced SD is priced that way because the manufacturer of origin deemed it to be defective.. not defective enough to toss it in the trash, but defective enough to not bother their highest paying vendors by passing it on to them. It may run, and run reliably, for years... but it really is a game of russian roulette with those things.