Where do your grandparent live? Maybe you can get order custom system and have it built by the people running the shop. If they live in Melbourne I can recommend
http://www.cworld.com.au/ and
http://www.scorptec.com.au/ they're a both a little pricey, you should be able to find a better deal if you shop around. Don't know any in Sydney, a google search should yield some results. Obviously they won't need a high end system. Maybe they can find a course or something where they can learn the basics?