Yes, I regret not dumping 200 BTC into a Single 10 months ago. That 200 BTC is now worth $28,000. I am so sad!
This the earliest orders will never (not in 10 years) recover the cost of capital. I am surprised they didn't raise prices earlier.
Regardless mining is already high enough risk. Makes more sense to wait until products are actually being shipped in timely manner so you can evaluate
That being said I may still buy a Single. I don't need to make a bazzillion % profit. If I can mine at cost, then I can use the Single as a Electricity to BTC converter, and help improve network security at the same time (by using p2pool). A win, win in my opinion. It all depends on your objectives.
Of course there is no reason to place an order today:
All sales are final.
You get higher price, longest delivery time, lowest return, and the most risk (no way out if things go south). I will wait until the backlog is gone and buy a Single then. Like I said it all depends on your objectives.