I doubt there will be many sales in the near future. Inflation is hitting everyone plus there are global supply chain shortages and the cost of shipping containers out of China has increased 5 fold in the last year. I highly doubt there will be any extreme discounts with current circumstances.
I do completely understand the cost. It wasn't that long ago that I bought my XXL 750. Personally I think RedSea tanks are an excellent affordable option at full price but this comes from selling custom tanks at the LFS where a custom Crystal Dynamics or Viso tank with a hand made stand was significantly more. It is hard to get a tank with the look, features, and support of a RedSea for less.