The 90 day shouldn't exist and should just be changed to buy, for the PSN price. Otherwise I have no issues with the costs as they are. Keeping in mind these are the PS3 prices. We don't know how much PS2/PS1/PSV/PSP rental prices will be.
Edit: It seems these prices are largely up to the publisher, as is often the PSN buy price. So basically they have 4 hours (lel), 7 day, 30 day, 90 day slots and the publisher fills the prices.