I learned about Massdrop from this forum. Here's a great explanation for how it works.
http://www.freshlypieced.com/2015/02...pplies-on.html
Once a drop has ended they remove the end price off the site to protect the vendor. If you're interested in a former "drop" you can request for it and they may release a similar deal again. It's a little confusing and it wasn't until I tried it that I figured it out. It's really become a bit addictive and I have been happy with the delivery of the product and open communication with the staff.