Laredo Tugger offered one potential reason for the price increase. I'll offer another:
When you first looked, Trekwood had 2,4 or more of the items in stock from a previous order. When you looked the second time, those items had been sold and no more are available in the supply system, so to produce one or two would mean a special order, special "one item" tooling (as the assembly line is no longer working). That would mean instead of pulling two from stock to send to you, the manufacturer, or whomever bought the blueprints, will have to tool, manufacture and assemble a "one time workorder" to fill your request. That is ALWAYS more expensive than building "a run of 100 or 1000 items".
Having worked in the aerospace industry, if it's on the shelf, it's relatively inexpensive. If it has to be manufactured for you as a "one time order" the price is substantially higher..... Maybe this is what you're seeing in the price increase???? Then again, maybe Trekwood is "just greedy".....