I currently have 24 stacks of items in my inventory, 2 completed golems, and 1 uncompleted golem. Yet the inventory page says I have 30 items. Is this a glitch? Is it anticipating items that are weeks away from completing at auction? 

Anyone know what's going on?

Golems don't count towards inventory slots.

I just did a little experimenting and stuff up for auction works differently depending on if you are buying or selling. Bidding on something you don't already have doesn't take up an inventory space, but even if you're selling all of something it still takes up a slot until the auction ends. Items in exchanges also take up inventory slots until someone accepts the exchange.