Hi. I'm a newbie when it comes to the Lightning Network. So say I want to buy a cup of coffee with BTC while I am travelling to a different country. But I don't have any LN channels open yet. The coffee store accepts LN payment.

I want to buy a cup of coffee just this one time at this coffee shop because I am travelling. I will never buy coffee at this shop again after I leave the country. How much would the transaction fees cost me? Would I have to open a LN channel for the current transaction cost of $30 to send BTC just to buy a cup coffee? Do I pay another $30 to close the LN channel when I am done buying my cup of coffee?