Lots of interesting sites but one thing not mentioned is the age group. Every age is different when it comes to anything you are trying to encourage a kid to try. Also, unless there are others of a similar age group involved, most kids tend to wander off to what others are doing. And remember regardless of people saying men and women are the same and at a really young age most things make little difference. But as the age groups and friends change with age, so does their interests.
Prior to just getting those starter kits, I suggest you think about the age groups, parental help in this field, boys or girls, friends interests, etc. Good examples are if your attempting to inspire interest with a group of boys of the baseball age, you may want to notice the baseball season is just starting. Or if the ages are of the oposite sex interest, coins compared to a dance is a loosing battle.
If the kids you are trying to inspire are of a really young age, don't waste money on a complicated, to them, book like the
Red Book. Yes informative but if at the age of still looking at the pictures and not reading a lot yet, interest will fade fast.
Lots of really cheap coins would help inspire some interest since if they are free of course. A magnifier from
Walmart. Some of those plastic looking flips or 2x2's also. At some coin stores they sell packages of really cheap plastic folding sheets of usually 3 different sizes. At some flea markets you may be able to find some bulk quantities of coins.
Naturally if you can find some cheap enough, those red boxes for 2x2's with two rows for coins.
Just remember the age group is really important.