it costs money to store/write a transaction to the chain (transaction fee) - binance smart chain is subsidised so runs at a loss/pretty cheap to store small amo

it costs money to store/write a transaction to the chain (transaction fee) - binance smart chain is subsidised so runs at a loss/pretty cheap to store small amounts of data on (if you did this on ethereum would be very expensive) - retrieval is free in that you can use a public RPC to retrieve the data