How to convert array value to single value?

Question

Kindly help me with the following PHP array conversion.

I am posting input values in get method, which gives following URL

page.php?fare[]=500&fare[]=400&fare[]=600

I use following method to get values

<?php $fare=$_GET['fare']; ?>

I can use foreach to print this values separately, but I want the data to print in following way.

$fare="500~400~600";

Kindly some one teach me how to do it. I am really confused. I thank you in advance.