Here are a few things you can buy with $200: one bluetooth-controlled fire pit, 100 lab-grown Impossible White Castle sliders, access to the 3 billion base pairs that make up all the DNA coiled inside your cells. Well, at least for the next 48 hours. Starting today, Cambridge-based Veritas Genetics will be lowering its $999 whole genome sequencing and interpretation service for just $199 for two days, or to the first 1,000 people who buy spit kits.