Hope the site goes beyond OKcash and bitcoin currency. As there are many other alt coins people are interested in so as to there way of investing money. The interface is very good for your website. Hope to see the more coins option soon. :-)
I am pretty sure this won't be an issue anymore since if you look at the mempool its mostly empty. If you are not in a rush you can get a transaction confirmed with 10 Sats/byte.
Next month when Segwit rolls out the transaction will be even cheaper. And then at the end of the year with the 2MB block size increase, transaction should remain cheap with enough scaling for the new demand being brought into bitcoin.