Unfortunately, there is currently no reasonably reputable exchange where you can buy NEX after Aphelion has closed its doors. Now the only reasonably safe way is to buy OTC in a reputable group on Telegram like House of Escrow. Don't use a possible scam exchanges like Tokok, if somebody wouldn't take the risk to bu OTC, just wait for an better exchange.
Can you vouch for the House of Escrow? I wouldn't recommend anybody to buy OTC. NEX will most likely be live until the end of the year, if not it will be live Q1 2019. And they will have listed NEX token. Just buy it there.
I am more and more sure that NEX is something that the space needs. A great product delivered could help the bear turn into a bull we are all waiting for.