If you absolutely cannot wait and are willing to give up the TEquipment discount, both Allied and Adafruit (lol) have the DS1054z in stock. Both end up being at least $30 more expensive (though potentially quite a bit more), but they do have them.
Adafruit is actually $449.00 plus shipping. Maybe because of the limited stock, of maybe they are just more expensive across the board. Either way, not great.
Even if another vendor had the same deal for immediate delivery, I would stick with TEquipment. They have offered us a discount, answer questions by phone and online chat, have good pricing even before the discount, been keeping us informed about their stock and they actually post here. They work hard to earn our business, so let's show them that good customers service pays off. For us, its worth building a decent relationship with a vendor.
And really, does a few more days matter? How long do you plan to own this scope?