style.js

  // option 1
  var Subscription = function (plan) {
    var self = this;

    // statics
    _.each(['dropdown_text full_rate id months name renew_rate special type'].split(' '),
           function(prop) { this[prop] = ko.observable(plan[prop]); })
    this.monthly_rate = ko.computed(function () {
      return (self.full_rate() / self.months()).toFixed(2);
    });
  };

  // option 2
  var Subscription = function (plan) {
    var self = this;

    this.dropdown_text = ko.observable(plan.dropdown_text);
    this.full_rate = ko.observable(plan.full_rate);
    this.id = ko.observable(plan.id);
    this.months = ko.observable(plan.months);
    this.name = ko.observable(plan.name);
    this.renew_rate = ko.observable(plan.renew_rate);
    this.special = ko.observable(plan.special);
    this.type = ko.observable(plan.type);
    this.monthly_rate = ko.computed(function () {
      return (self.full_rate() / self.months()).toFixed(2);
    });
  };

2 is way better IMO, meta-generated stuff is just annoying to compute in your head