Just purchased a 1989 Topps Traded Barry Sanders RC Graded BCCG MINT 10

I dont understand this Beckett Collectors Grading thing, I know that they cant be as valuable as real BGS grades. I also dont understand why a grade of 10 is only MINT and not GEM MINT!????

I only paid $5 for the card, If anyone can tell me the Mint Graded book value on this card I'd appreciate it. Also in the guide is it considered a BGS? or just an "other" MINT?????

either way I have no clue of the BV I just bought it thinking it was a good deal...