Why 300?
My guess is this: this is a special test market offer. Those who ordered early will feel special about owning early, will write reviews and talk about it, building interest, so when the October 1st date rolls around, the site gets a lot of orders for not only this trick but the others that are coming out on that day.
---And there's nothing wrong with this as a marketing move. It's fun for the consumers and very effective, too.
Hell, it worked on me. I bought mine outright. I'll have it next week and you bet your a-- that I'll be performing it, reviewing it and talking about it.