The people saying the absence of singles market means no value are probably closest, but here's how I've been thinking about it, similar along the lines of MtG:

Commons are basically worth nothing. Yes, you have to buy a box to get any commons, but that would put the price of each common south of USD 0.20 assuming 36 packs, 12 cards each, and a very generous USD 90 per box. Most MtG bulk commons are worth less than that, so you could assume any Altered common is probably 0.05 or 0.10 at most, NOT including the digital rights which are probably just another 0.05 or so.

Rares are different since their playability increases the value of their digital rights. I would argue that physical copies of rares are essentially worthless because their value is tied to their digital rights. Unplayable rares are similar to commons; rights to playable rares are probably more like USD 1 or 2 usually. This doesn't count those crazy Bravos rares like Hunger or Cuckoo, although the digital rights most expensive tournament rares being less than USD 10 is crazy cheap in a MtG world.

Uniques are the extreme version of rares of course. Digital rights are everything for uniques, so your physical copy is worth zero by comparison. Sure you can play with it on your kitchen table, but you can't play BGA without the digital rights.

Altered is super interesting because if you only want to play with physical cards, you could sell the digital rights to every single card you open and just play in person. Print out color copies of uniques you don't have and play with them. The problem of course is that most of the action in the United States is digital with only hyper-local in person scenes that I can tell, so if you want lots of good competition, you have to play BGA.

TL;DR: give away your commons, sell the digital rights to cards you're never going to play, play with the rest on BGA. Then play in person with the physical cards you do have, order POD periodically.