You'd have to be storing absurd amounts of stuff for it to add up to thousands of dollars. from their docs:

Glacier is designed with the expectation that retrievals are infrequent and unusual, and data will be stored for extended periods of time. You can retrieve up to 5% of your average monthly storage (pro-rated daily) for free each month. If you choose to retrieve more than this amount of data in a month, you are charged a retrieval fee starting at $0.01 per gigabyte. Learn more. In addition, there is a pro-rated charge of $0.021 per gigabyte for items deleted prior to 90 days. Learn more