We strive to have things on the shelf ready to go. The issue right now is with reduced fabrication capacity, material shortages and way higher demand than what we anticipated we are struggling to keep all items in stock all the time. We have upped batches as much as we practically can to try to catch up with demand. The other issue with making large batches of items that have to sit on the shelf is warehousing. It is a fine balance between having products in stock, having enough space to warehouse them and timing a market that is very unstable right now.
As for the 80 stuff, we actually produce way more stuff now than we have ever done before. Still a hugely popular market.
We never take peoples money before we are ready to ship the products. I have seen to many companies get in trouble when something goes wrong and they can not deliver on time, but they have collected a bunch of deposits. Hence the email notification system. It is pretty much a first come first serve basis.
That said, a batch of 20 of these sliders will become available on the site in about a week or so. These might sell fast, but I do not believe they will all sell out in the first day based on the number of people signed up to be notified.
This is not excuses, just an attempt to put some clarity on product availability.