Probably need to be careful how you word things. Some people, especially those new to Mac, could get confused and waste money. i.e. Snow Leopard is an update to 10.6, hence why it is only $39 at the store.
Would either need an original install disk with Leopard (then upgrade to Snow Leopard) or get an install disk that has 10.6.3 or newer on it.
There are sites that have this for download, but one site is for pirates. 😉