will increase your cost of goods sold (COGS)
That's only true if you actually sell that inventory before the end of the year. Remember, what you pay for inventory is not deductible until the tax year you actually sell that inventory. It flat out does not matter in what tax year you purchased it either. So if you buy now it will make absolutely no difference what-so-ever to your 2019 tax year bottom line - unless you actually sell that inventory before Dec 31st of the tax year.
So if you can get a good price on it *now*, then buy it *now*. it makes no difference in your tax liability until the tax year you sell that inventory.
The only thing you have to be careful of, is that some localities impose a "tangible property tax" on any unsold inventory you have on Dec 31 of the tax year. I'm not aware of any states that do that. But there are a few localities below the state level that do. Hopefully, you're not in one of those localities.
