I'm not as particular as you are about the grade so I don't have as much trouble finding coins that I like. In my opinion I got some good deals. Is SA's economy going poorly? That could be a reason for a price decline.
I presume South Africa has taken a big hit from the recent commodity weakness and the collectors I know there claim this is the reason for the recent weakness in the coin market but I don't believe it. Unlike the US and a few other countries, the local collector base isn't large enough where there is any demonstrated correlation between economic conditions and the price level. My explanation for it is a combination of adoption of TPG, the run up in gold and silver prices and the prior national mania in the 2008 90th BD Mandela 5R (which accounts for over 50% of the 390,000+ coins in the NGC population report) created a (limited) bubble in Union and ZAR coins. Metals are in a bear market (for now) and the Mandela mania is over resulting in a "buyer's strike" and speculators dumping their "investments".
I tried bidding on this South African coin in the Heritage auction. I bid twice the estimate - and I got destroyed! http://coins.ha.com/itm/south-afric...35.s?ic2=mytracked-lotspage-lotlinks-12202013
Just went to the CSNS coin show in Schaumburg, Illinois. Never been to such a large show before! Not many world coins around, other than high-buck stuff and ancients. Even the dealers selling Lincoln Cents only seemed to bring their best, highest-priced examples. Hard to find what I was looking for! I did see Charmy (the Penny Lady) there and wanted to say hi, but she was busy with a customer for the longest time. I didn't get any world coins, but I did manage to find a few Lincoln Cents (dates 1909 VDB, 1910-S, 1911-S, 1913-D, 1924-D) in EF. So, not a total loss...
I also went. I posted some of my pickups in the Newest World Coin thread, but I agree there weren't many foreign coins, and most of what I did see was ridiculously priced. I got a few though. All you need are a few dealers. I ignored the vast majority of them completely.