Right on the previously announced schedule, today the Moto E4 Plus became available to order in the US. The phone is currently only actually in stock at Verizon, where you can have one for a prepaid plan if you shell out $129.99. That's the cheapest price right now.
At the same time, big third party retailers have started pre-orders for the unlocked Moto E4 Plus, which will be released on August 11. If you don't mind seeing Amazon's ads and offers on your phone and you are a Prime subscriber, you can buy the device for $139.99 (with 16GB of storage), or $159.99 (with 32GB of space).
On the other hand, if you want an ad-free experience note that the E4 Plus' normal pricing is $179.99 (with 16GB of storage), and $199.99 with double that amount. These options are offered by Amazon alongside B&H, Best Buy, and Newegg. The E4 Plus' main claim to fame is its huge 5,000 mAh battery, since it's otherwise a pretty run of the mill lower-midrange smartphone.