I think those are the best sites for checking the value, I think steemprice.com is another one?

You can find SBD on polo as well, but the volume is much lower, usually around 10 btc per day so you may have to scroll down quite a bit to find it. You won't find SP on any exchanges, but when you power down, your SP gets converted into Steem. Luckily SP keeps going up, so even if the price of Steem is flat you would make a profit eventually.