Have you tried your local supermarket? They are easily available here in Australia off-the-shelf. And they are also easily available from Chemist shops. Be careful with them, tho'.
Why do you need laxatives?
You do know that laxatives can be dangerous if not prescribed by a doctor right? They can cause dehydration if people over use them and furthermore can cause your bowel to become lazy which could cause you to end up with chronic constipation.
I suggest that if you are constipated to rather eat a lot of fruits and veggies, cut out pasta and get in foods that are high in fiber. Laxatives should be a LAST resort, not a first one.