I read on Pornlist some where that day time swingers parties are generally a scam. All the people listed have there faces blurred on this site, they will probably claim its for discretion. Not saying that this is a scam, best you call them and ask for quite a few referrals first before you part with a single cent of your hard earned loot.
They cliam to have started in March 1996, but the domain
www.amateurxxx.co.za was only first registered in 2001 according to Uniforum public records.
On the site they claim to be based in Sandton but the address on Uniforum is 21 ninth ave, Parktown North which is hardly Sandton. Unless Sandton rencently moved to Parktown.
For me there are too many things with this that don't add up for this to be for real. Tread carefully and beware.