i can only compare it to MyShoppingBox and it's much much better getting it direct sa Amazon.
1. you get the item in 4-10 days compared to the same (most cases mas mahal pa) shipping price sa MSB that will take 45 days at least
2. cheaper din since the shipping fee is fixed. may added sales tax din kasi when shipped within the US (depends how much from state to state) to the 3rd party shipper. so you have the retrailer shipping price+tax+3rd party shipping charge. easy math
3. you do not know how big the box Amazon or the retailer will use to ship the item (Amazon is notorious for using big boxes) and that is a major factor how much the total cost will be using the 3rd party shipper as they compute the box dimensions and not the actual item.
Anong item ba yan if you don't mind me asking? baka naman meron na locally like sa Shopee at Lazada or somewhere else that you're not aware of.