The advantage of buying from an individual is that they (or someone before them) have taken all the risk. Especially if you are not an experienced operator and mechanic on these, you take a significant risk buying one truck. Even if you inspect it, buy it "right", and think you can drive it out you could end up with a good looking truck that needs $700 in brake parts, a head gasket, a water pump, an injector pump, a transfer case, a transmission or any other part you could name. At one time or another I dealt with 'em all on either my trucks or buddies trucks.
Even after spending 29 years around these and supervising 68 mechanics at one point, I had mild butterflies the first time I bought from GL.
Sometimes prices spike early and sometimes they spike in the last few minutes.
Personally I use parts of the advice from several of the respondants to this thread.
GL bidding is "dynamic", with a 15 minute re-set. This means that if someone bids just seconds before the auction is scheduled to close, it will remain open for 15 minutes from the last bid. There's no Ebay style sniping tricks that will help.
I save all the items I'm interested in to my "watchlist" and I set an upper $ limit, before the auction starts. When the bidding gets to that figure, I'm done. I might bid early while price is low just so I can keep an eye on how the bids are coming in. If I'm going to be around the farm I'll usually wait to bid at around 15 minutes prior to the auction closes to bid.
One interesting thing is that if there are a large number of trucks at a single location you will often see trucks with early bids that are very reasonably priced which sell without spiking late. I think that what happens is folks concentrate their attention on the trucks with very low bids, then the moderate bid trucks close without competition and the last few trucks get bid to the moon. A big advantage of a large auction is that there could be several trucks that you would be willing to buy and you can wait late in the auction to concentrate on the best deal.
FWIW, I sell enough trucks and parts to make this a self supporting hobby. I am generally prepared to buy three trucks to get what I really want. I might buy a great looking low miles drop side truck with a sprag transfer case. Then I'll buy a rough truck with a winch, air shift transfer case and hard top and, maybe a third with great XLs. I'll move the winch, hard top, transfer case, tires etc to the truck I want to keep and sell the other two. That way I pay for what I keep, get my money back and, usually, make some extra to go looking for a bigger, better deal.
Lance