Sometimes the risk (self-install) outweighs the reward (saving money) especially if there is an unknown factor with the tenants ability to do the install. 

The builders don't care about your plans but even if they did it will not affect your ability to use them.

Tax Benefits: Real estate investments offer a variety of tax benefits, including depreciation deductions and the ability to defer capital gains through 1031 exchanges.

I don't have the ability to spend all the marketing dollars to get to the seller directly like the larger investors do.

Home Depot, Lowe's, Menards and even local stores like Ace are one stop shops and what you might spend in terms of a little more, you regain in terms of time saved and the ability to sign up for Pro accounts. 

Some states you're required to include it in your determination of ability to pay, others you are not.

If it is, it will slow down your ability to borrow money for another purchase.

You can still make money - but your upside and ability to raise rents is dictated by the city, not the government

Also including the tenant friendly restrictions limiting any ability to evict still in nj

You don't want to put yourself in a super tight spot where you don't have the ability to pay for a large expense (which are inevitable)You are super close!!