i was offered my aniversary pack for 21 bucks, and i thought it was a good deal till i found out that others are paying a sigle dollar for theirs, just wondering why some players are being taken advantage of and being chargd 21 times as much as others for the same pack

Their pack probably had less stuff in it than yours if they were getting it for so much cheaper.  The game uses an algorithm to determine what packs to offer you, based primarily on what packs you have purchased in the past and the dates of those purchases.  If you buy larger packages, it will offer you more of the large packages, which are usually less efficient than the smaller ones but do let you buy a larger volume of stuff.