Earthquake Early Warning System

I wanted to Build a Network of Sensors to warn People of impending earthquake. Theoritically it can only warn 30 seconds up to 180 seconds, this can give you as much time possible to get away from danger spots like near windows, hanging objects, mirrors, or tall furniture and if you are outside keep away from buildings, power lines, trees and get into the open.
Initially I have ordered from ebay my parts but half of my orders get lost in transit. Ordering locally ensures me of getting what I wanted but increases cost up to 250%. I hosted the website on the cheapest possible hosting, just to lower my cost, I have yet to see the response time it will give me.