EV is relative to the cost of acquisition, and I can tell you for certain that our prices (and consequently your prices) vary a lot per set. Ravnica was super cheap that time, I'm not so certain it will be again in the future. Obviously the interest in the deal is relative to the pricing, and it's hard to vote on things without knowing the price. We won't list products unless we think the price is competitive, and we specifically listed products at pack prices due to their packs being competitively priced (I agree gatecrash as a box wasn't very good, but as a 3-pack, I'm pretty sure nobody else on the internet sold 3 packs shipped for $10.00).
As a very rough ballpark, I think it's useful to vote thinking "if I could buy --any edition-- booster for 25-50 cents less than the typical online price, it would be --X--"