I've also been powering up gradually in small increments on SP every time the price goes down. I split my buying some I buy on the market and some I use that 1 week exchange thing for. That way I can hopefully balance out the price a little bit in case it changes significantly.
I agree with your thoughts on Monero. I don't think it will sustain a high long term price either.
I will check out @matrixdweller - thanks for the recommendation.