Yes, that is correct for that sump, it is actually about 20 gallons and the lid is included, the 15 kit has the same dimensions but no internal baffles and I suspect it will cost less as a result, but likely not much less. Because they are glass and have to be really overpacked to make it here in one piece they cost a fortune to ship and that is most of what you are paying for. The box it will come in is 30 by 25 by 25 and ships at a weight of 90lbs regardless of actual weight because of this size. It costs us about $100 to get it here from Germany and I do not have it in stock. I also could find no pricing on a 1591.000, it is Good Friday and the factory is closed, but I will try to get pricing ASAP.
FWIW, I have a 1591.000 that has one broken pane that I cut away and was hoping to someday repair with a new pane, it is all ready for a new pane to be siliconed on, if you feel comfortable with this I would be willing to send it to you as is for only the price of shipping. It doesn't have a lid but the lid is just Polygal and most plastic shops sell this material.