I was asked for a resolution to our low AC Ranger/Druid, so here it is.
First, this thread was based on him only in the loosest of senses. He didn't have 100k to spend, for openers. The player wasn't writing down the cash portion of any of our treasure picks, so he almost nothing in terms of cash.
We backtracked to the last sizable loot split to determine what he had taken from it, and after seeing that it was pretty much nothing, the group voted that he had the cash value. We also had the loot split we'd just done. Add in what he had actually written down and we had our budget: 73,260.
Since he already had Bracers +6 and a 20 Wisdom, the Monk's belt made a lot of sense. He had some masterworked "Leather scale" armor, but it didn't do anything for him other than look good, so he dumped that. Cheapest +5 AC boost in the book, which took him from a 25 to a 30.
Next he bought Gloves of dexterity +4, which helped his AC, his Initiative, and his archery.
He already had an Amulet of Natural Armor +3, so the Periapt was a non-starter. It would give the same AC bonus per GP spent as the Natural Armor amulet, if he were starting from scratch. As it was, he'd get half value selling the amulet he had, while paying full price for the Periapt, so it made no sense economically.
There was some debate about an Animated Shield, since the Monk's Belt doesn't work when you're wearing armor or shield, but it was ruled that it wouldn't conflict when "in use", since it wouldn't be held or wielded in combat. I'm sure there's been a lot of debate over that combination, and I'm sure there will be more in the future.
So his AC is now up to 35, having spent a shade under 40k on it. He could add to his Ring of Protection or his Amulet. He could also add to the plus on the shield. So he has room to grow with this build, which is a good thing. At our level (17/18) he's only a couple of points above non-combatant standard.
As for why the Ranger/Druid combo: The character started as a Ranger, and we had a druid in the party. The Ranger was more the huntsman than the naturist, but he liked and worked with the Druid. In character, he attributed his own development of magical ability (Ranger spells) to his working with the Druid. The Druid died, and he kind of took over that role.
A lot of the PCs in our party have sub-optimal multiclassing. That's one of the reasons why my Bard is the most powerful offensive spell caster in the group. I'm not bragging so much as observing a sad reality.