In Reply to: Slightly confused with VOA posted by lindsey on Thursday, 20. July 2006 at 17:18 Bali Time:
the top of the page. Look a bit above your post and in green boxes you will see Visa Regulations, click on it and all the info you need is there.
And yes your mum and her sisters will be able to purchase the $10 US visa for a 5 day stay, provided as Bart points out you are one of the nationalities that are required to purchase Visa on Arrival.
hope this is some help...cheers :-)