Who pays for the printing cost of the books sold through Pothi.com?
Generally the books are printed on demand i.e. only after an order has come and has been paid for. Hence, neither the author nor Pothi.com needs to pay for printing cost upfront. You only need to pay if you have placed an order.
If you are ordering copies for yourself, then you pay the author price and shipping cost for the copies
If you opt for one of the premium distribution plans, they you pay for the printing of copies initially, which is reimbursed with the royalty as the copies sell.