Wow. For 20 productions of a 20 page book with the cheapest materials, it'll run you $371. Youd have to sell that book for at least $19 just to break even.

I'm only looking to make ONE hardback book for myself. It's not the cost, it's the lack of choices.

I'm going to take an educated guess and assume that they're all using standard laser printers to 'publish,' and they have the odball sizing so they have more leeway in trimming and paginating. (8x10, 10x8 print on 8 1/2 x 11 paper; 13x11, 12x12 print on 13x19 paper, the small stuff print on 8 1/2 x 11, possibly multiple pages per sheet)

They don't want to go to the trouble of making 'normal' sized books, as those will require customizing the page dimensions or dealing with more than the 'usual' amount of 'waste, which will increase their costs.