30/35% is terrible IMO. Even if a prebuilt recycled at 95% value, you'd still be getting the same cards over and over again. With the midlawt prebuilt, I bought one, recycled just about everything, and bought another, just to get the 3rd EX Zuga. Releasing prebuilts as they are for 1500 gran would be a slap in the face of the majority of new/free players.
Look, if someone is a collector and wants ALL THE CARDS, then they can spend. If someone wants to make metas full of OMFG RARES, they can spend. If someone wants all the prebuilts, they can spend.
But if you're just a free player looking to have a few competitive files, you should be able to get at least that. If the only role of free players is to just be fodder for spenders with their accounts that they spend hundreds (if not thousands) on, then what are we talking about?