We used a wanted ad to find our Grade A (and other horses we have bought too). Always got a great response (once we sorted through the rubbish) and always ended up with horses we were very happy with.
You shouldn't have any problems as the market is often flooded with Grade A & B's and this way may be a cheaper way than using a dealer.
Good luck
weve put an ad on horsemart
no response as of yet
we dont mind buyin from private either but i havent seen any for sale
were in essex but will travel anywhere
nothing horriffically priced but will pay substantial amount.