Welcome to crypto currencies! That difference is nothing unusual. Most Litrecoin trading happens on Chinese exchanges, OKCoin and Huobi in particular, and Chinese investors are often prepared to pay a premium.
To save the fees and spread, you can always transfer your USD to Coinbase as USD. Once the funds have cleared - transfer instantly the USD to GDAX exchange - from there you can control your buy - setting your own price. Once converted to either BTC or LTC - transfer them back to Coinbase and then to your personal wallet.