The answer to this will vary depending on the size of the set. I will use Khans of Tarkir as an example, which has 101/80/53/15 commons/uncommons/rares/mythics. According to [this](http://boardgames.stackexchange.com/a/13418/5783) answer, - 1 in 6 packs contains a foil - foil mythics are several times more rare than foil rares. I interpret this to mean that distribution is equal to the total number of unique cards of each rarity, e.g. for Khans you'd expect 101 out of every 249 foils to be common, and 15 out of every 249 foils to be mythic. The question of "how long does it take to randomly collect one of each item in a collection, with replacement?" is called the [Coupon collector's problem](https://en.wikipedia.org/wiki/Coupon_collector%27s_problem). On average, - You need to get **524 commons** before you have one of each. There are 10 commons per pack, so you will need to open **52.4 packs**. - You need to get **397 uncommons** before you have one of each. There are 3 uncommons per pack, so you will need to open **132.3 packs**. - You need to get **241 rares** before you have one of each. There is one rare per pack, except in the 1/8 chance of getting a mythic, so you will need to open **275 packs**. - You need to get **49 mythics** before you have one of each. There is one mythic per eight packs, so you will need to open **392 packs**. - You need to open an average of **14.7 packs** to get one foil common, so you need to open **7702 packs** to get one of each. - You need to open an average of **18.7 packs** to get one foil uncommon, so you need to open **7423.7 packs** to get one of each. - You need to open an average of **28.2 packs** to get one foil rare, so you need to open **6796.2 packs** to get one of each. - You need to open an average of **99.6 packs** to get one foil mythic, so you need to open **4880 packs** to get one of each. The question of "how long does it take to randomly collect N of each item in a collection, with replacement?" is called the [Double Dixie Cup Problem](http://stat.wharton.upenn.edu/~shepp/publications/1.pdf). There doesn't appear to be a formula for this, but from my experiments it seems like N=4 takes about three times as many trials as N=1. So by my estimate, to get four of every regular and foil card in Khans, you would need to buy **22,269 packs, with an MSRP of $88,853.31**. This seems somewhat more expensive than just buying singles, so I can't recommend it.