I seriously doubt most vendors care to compete with Amazon on price. Amazon makes all of their money from locking you into their services and platforms. That's not something other tablet vendors can do. Apple doesn't need to compete on price due to the size of their ecosystem and the quality of their products. That leaves Google which did something similar to Amazon with the Nexus 7 but can't necessarily continue that trend without damaging relationships with their hardware partners (All the OEMs currently making tablets).