In December, it was done right at the stroller rental counter. Instead of paying for the day, you just tell them you would like to purchase X number of days. They will give you a strip of coupons for that many days and you pay a discounted rate. On subsequent days you by-pass the payment counter and line, and go directly to the CMs who are giving out the strollers. They take one of the coupons (and stamp your tear off part of the coupon) and give you a stroller right there.
Hope I explained that well. It was the way to go! Much faster.