Follow Doc Moore's strategy (if you have the time and the $$$ to do so).
1- A few weeks before sale, visit all the farms that have yearlings subscribed and take note of the ones that stand out to you.
2- On sale day mornings, set up your own personal ultrasound and x-ray machines in a quiet corner.
3- Have the consignors bring the horses you had previously noted over to your own personal space at the sale so you can x-ray and ultrasound them, making sure they have clean legs, knees have filled etc....
Now, as a layman bidder, put a $$ value on the ones you like (or even don't like)
And if possible, carefully watch Doc Moore and see what horses he bids on based on the homework he has done over the previous weeks.
If any horse he bids on if about to sell for a price less than the value you put on it, there's a pretty good chance that you're getting a good deal.