I look in the local papers, or use word of mouth. You are much more likely to know the person selling it (either by hearing about them directly, or a friend-of-a-friend will know them kind of thing!) so much less likely to be sold a horse which isn't quite as sold i.e. doped, lame, wrong age, wrong height, no experience etc etc.
As much as I love reading the horsey mags, I would never buy a horse from them as almost impossible to get a rating on the vendor or vet, so I wouldn't risk the cash!
gorgeous grays! mine is a problem horse i paid £900 i think hes worth it... i found him on horse and hound online (he never made it in the magazine as i brought him asap as too meny phone calls for him there was two other people there same time as me i was the lucky one that was there first so i had first refusal, you got to be in there quick and act fast for a bargain horse.. they dont stay there for long before someone snaps them up! i love the first and last gray wish i had that sort of monie... altho you could go see them and offer them a price?