There are probably three tin choices for every one bulk. But that doesn't mean that one could not smoke bulks happily for the rest of his life. But it seems that most tobacco manufacturers opt to tin their tobacco and blend it with an eye toward a distinction that can command a higher price. For instance, Chenet's Cake. It was being sold for ~$10.00 a tin. Due to its lower price on smokingpipes.com and the discount available for buying quality, that brought the price of a pound down to ~$70.00/pound. But being value conscious, I and others requested a bulk offering, and they replied with a ~$50.00 price per pound (though 8 oz tins have yet to be made available). So for the bulk sale sp is willing to lose $20.00. They are willing to tolerate less profit. Many manufacturers prefer to forego a bulk sale in favor of the higher margin of tins.
So yes, tins are more expensive than bulk, Semois more expensive than most tins, Condor and the other UK plugs more expensive than Semois, and Stephen Books fine aged tobaccos more expensive than the UK plugs. It comes down to how badly you want the more expensive tobaccos and whether you are willing and able to suffer the hit that buying them has on other parts of your budget.
In the end I think good enough tobacco is good enough most of the time. I think the smoke rendered by concentrating on both the flavor of the smoke from good enough tobacco paired with good smoking technique, the sipping and savoring of the tobacco, being in command of the pipe, produces the best smokes.
But whatever the amount of tobacco I have cellared does not cause me to not want adding more. I am currently lusting after tins of Sillem's Commodore Flake, and if I love a tobacco no less than 10-15 pounds cellared is enough. But even 10 pounds costs $1275.00 dollars. Though entirely covetous, I probably will need to buy only 20 tins or 1000g, at about $250.00. And although with a dissatisfied heart, I can live with that.