With the passage and signing into law of H.R.1, aka, The Tax Cuts and Jobs Act, the deduction limit for Section 179 increases to $1,000,000 for 2018 and beyond. The limit on equipment purchases likewise has increased to $2.5 million.
Further, the bonus depreciation is 100% and is made retroactive to 9/27/2017 and good through 2022. The bonus depreciation also now includes used equipment.
Section 179 can be extremely profitable to you, so it is to your benefit to learn as much as possible.