硅谷居士: 请问国泰纳指基金513100的买卖细节

I learned this from you last summer. Thank you.  My relatvies in China did buy later last year and have decent gains on this. 

But they told me there was buying or selling preimium (up to 13% in volatile days. Hinted a few % in normal trading days) now. In other words, market price is hard to get (just like old time USD needs to bought at preimium compared with market price). 

Is there any way to avoid or minimize this premium?