Add GMA as a grading company option

GMA is a cheaper option for getting cards graded than the other options listed. While it might not increase the value as much as other more renowned company's such as PSA, it's a more viable option for cards who's prices won't be worth the PSA fees. Current GMA prices are as low as $10/card. PSA's cheapest option is $30/card and the card must be valued at over $500.