My two cents as someone who has done a couple breaks in the past:
First, if you are the person breaking the case, most people tha tparticipate do so understanding that your team cost is covered by everyone else's payment. You are breaking, sorting, shipping, and collecting payment, so most people are okay with that. If they aren't they shouldn't participate with you. There's nothing wrong with that! However, if you are breaking a higher-end product, you shouldn't so this. Here, you could be trying to pass off a large amount (generally, anything $50 or more is what I consider) and that isn't cool.
Speaking of higher-end products like Plates and Patches, you pretty much have to break a case (like spazmastic said). Rather than selling teams in the break, sell spots. For instance, 2017 P&P comes as a 12-box case, five cards per pack. That's 60 overall cards. A case runs about $1,200 (roughly). You could sell 10 spots and ask $120 per spot. Then you break your case online. Once you are finished, everyone that purchased a spot is listed in a random list generator and a random order will be generated. Then you conduct a snake-style hit draft, meaning that the first person on the list gets to pick a card, then the second, then the third, etc. until all 10 participants have picked a card. Then you go back through the list in reverse order, with the person who is 10th on the list picking a card, then the 9th, then 8th, etc. You would do this a total of six times, until all cards have been claimed. That's a pretty fair way to break higher-end product.
As for the lower end (as a baseball guy, I'm thinking all the Topps flagship products and even stuff like Heritage, Ginter, and Gypsy Queen), you can use the model you mentioned above. In breaks like this, most people are just trying to get a team set with a chance of getting a hit or a parallel or two. It's much easier to do the buy one/get one model here.
Then you get products like Bowman, which features a team with seven or eight different players that have certified autographs in the product and other teams that have no players with certified autos. The best thing to do then is to essentially determine the per-hit cost of the case, then determine how many hits per team and multiply accordingly. This can get a little difficult, especially if you consider parallels a "hit." I just bought into a 2017 Bowman's Best case break yesterday, selecting the Rangers (who had only two players signing in the product) and it cost me all of $10. Other teams that had more players sign, like the Yankees, went for $140+.
Sorry for the long-winded post, but I hope that clears things up. And now I want to do a Heritage case break! Ha!
My Cardboard Habit
PC'ing Matt Harrison, Rusty Greer & anything Texas Rangers
PLEASE NOTE: I am currently reorganizing my collection at the moment, so I will not be trading until I have everything in the system. Thanks for understanding!