Further: if they have the budget allocated, they will spend it. It’s that simple. Doesn’t matter what it is on, and going over budget in this political climate is a plus because they can justify more money for next year’s program request.
In this article’s case, expensive items are often novel and have some weird context or specific change attached (Stinger missiles, for example could have a lot of reasons to be expensive now) and the trash can is probably a metal galley can that is not cheap to produce and deliver to site, but it makes a good argument about price gouging generally due to lack of controls across a number of products.
Like most things the answer is not that this is completely unreasonable but rather that it could be better if we did something about it.