This is where the fun begins!
Googling through all those different websites, combing through the ads looking for those diamonds in the rough, the potential partners, the good legs, the cute noses, the flagged tails, and more, all the while trying to decide if this one, or maybe THIS one, will do.
I tend to check several different websites, opening new tabs for any ad that may even seem to have what I'm looking for. Since my list is more vague on search engine specifics like breed, age, height, etc., I would simply put in general stuff, most importantly the budget, then go from there.
With this type of searching, you see a whole TON of different types of horses, but because of where I live, it's mostly a lot of ranch bred quarter horses with a few friesians and tb's mixed in. Sometimes you'll hit on a warmblood, or you'll find an ad for a sport horse breeding farm, but those would generally be getting into the upper ends of the budget (but always fun to look at and drool over).
Once I have a ton of tabs open, I'll go through and really look at them, see if they fit the criteria of part 1. If they don't, tab is closed! If they do, it stays open for more rounds of reaping. Once these tabs are refined down to a manageable amount, that's when I start contacting sellers for more information. Usually about half of them will come back stating either horse is sold, horse is no longer for sale, or horse is out on trial until next month. The ones on trial will be put on the back burner if they're really quite special, but if not, tab is closed. Depending on what the owner tells me, we move on to part 4....
The Test Ride
*cue ominous music*