>>45759405>best price per packDepends on the set but for an example, Vivid Voltage is the most current set, never pay more than MSRP for it.
>what format should I aim for?I don't play the game much, and especially not with real cards, but this depends on how much you want to learn about the meta and how much you want to spend. Standard is a much smaller format than expanded (obviously) and is easier to get into because the cards in the format are generally still in print.
>but are their products to avoid or is anything worth nabbing, like promo boxes, tins, 3 packs, balls?If you're new, it might not be a bad idea to grab an Elite Trainer Box as that gets you packs, sleeves, dice, counters, and a box to store cards. You don't /need/ to get one, as you can get all of the bonus stuff elsewhere. As far as promo packs/tins/balls go, generally they only mean anything to collectors so if you're more focused on the game, they might not always be worth it.