You can obtain funding if you are in a university department, reduce the number of colour plates, get a student concession, etc. But at the end of the day, it's worth paying for the honour of publishing in top journals. You won't regret it. Few ever regret paying too much for a fine item, but everyone regrets paying anything for rubbish lol. And your question should read: '...pay fewer publication charges...', not '...pay less publication charges...'. Grammar's important! Ask Weird Al lol :-)