The full spoiler for Eternal Masters has been up for a little while now, and we are starting to get reasonable calculations of the set's expected value. It's not surprising that things got less exciting after we saw Mana Crypt, though getting the exact number of bulk rares is very relevant in EV calculations. SaffronOlive did an EV calculation on MTGGoldfish, and he figures a box has a buylist EV of about $200.
This number isn't surprising, and I've consistently warned against purchasing sealed Eternal Masters above MSRP, and honestly it may not be wise to open product even at MSRP given that the value of cards in the set will generally decline as product is opened. One question mark that is relevant going forward though, is the price point of cards that will be printed in foil for the first time in EMA. It's unclear what these cards will be worth at this time, though for the relevant Legacy, Cube, and Commander cards I would venture that a lot is a good estimate. Here's a list of all the cards being printed at foil for the first time:
I don't expect foil Roots to be worth anywhere near the cost of a pack, though there are plenty of cards on this list that will command substantial multipliers. Legacy staples like Baleful Strix and Toxic Deluge are going to be filthy, and Cube staples like Winter Orb, and Worn Powerstone will also command significant multipliers.
As copies of these foils start entering the market, I expect they'll be rather volatile initially, though ultimately getting in soon on the sought-after cards on the list should yield good returns provided that these cards don't see a second foil printing.