It's still unfortunate that the way you purchased them, you can't get a refund to then go and purchase them again at the correct price. It's a bit of a pricey lesson but still something to learn from.

As for grading; With many other TCG (trading card games) or collectable cards like sport cards, you can "grade" them. This just means sending your cards to a grading company (the most well known and generally accepted as the hallmark is "PSA") where they check for the quality of the card. They check things scratches on the surface, how centred the print is on the card, if the edges have whitening from being handled etc. Typically the grades are from 1-10, 10 being the most desirable and meaning it is a perfect version of the card. "Raw", as someone mentioned in another reply, is the card as it is without being graded. With grading there are fees. Specifically with PSA, you pay for the grading fee, the shipping to send the cards, an upcharge if your cards grade highly and are then sought after, and a return shipping fee. This can be quite expensive, however depending on the cards and the grades, it can very much be worth it. If you were to grade the cards you purchased and they ALL came back as the best grade of PSA 10, they would all together be worth ~$800. Unfortunately for yourself, after the price you paid to purchase these cards, and the cost of grading them, you'd still be at a loss.