Q.: Cryptocurrency rates change so much that it is impossible to calculate the price in cryptocurrency. How will prices be fixed on your site?
A.: Every seller will be able to set up the currency that he wants to get as a payment.
If the sellers sets up the price in fiat (USD, EUR, RUB and so on), then there is nothing to worry about because there will be no volatility issue for the seller. Once a buyer pays in ETH/BTC or any other accepted currency, but different from the one which the seller has set, an internal exchange will convert the received currency into the seller's one instantly at the current rate. This is one of the main Storiqa's solutions which gives the opportunity to sell for cryptocurrency without bearing exchange rate risks.
But if the seller sets up and fixes the price in any cryptocurrency, then the seller has to accept all the volatility risks. It can be reduced by fixing the price in stablecoins (we are going to implement stablecoins like USDT as example) or constantly monitoring the currency price and changing it in case the rate has changed significantly.