Paying excess baggage charges up front is normally cheaper than paying at check in.
Depending upon how much he expect to take, and the charges involved, it could even be cheaper for a friend to fly with him and have a double allowance as long as the friend get straight back home afterwards and doesn't bring their own stuff.
Or do what others do, bring it a bit at a time. On moving to the UAE, I got the essentials in the 30kg allowance but the next three rips were also 30k but i went back empty each time, and brought another 30kg.
Even though I now have Gold Status, it still only gives me 46kg so sometimes you just have to make do or pay up.