How to tell husband purchasing a $700 phone is not a necessary purchase?

My husband and I live paycheck-to-paycheck as it is. We have two little ones, both of whom are still in diapers. I have been sent to collection over a hospital bill that had been in dispute with the insurance co for 2 years. So needless to say, any extra income we get should be put into savings or used to pay down our debts.

Well, a couple of family friends moved away. They gave a lot of their things (tools and such) to my husband, all of which are still in very good condition. We just can't keep everything, so he wants to sell the power tools and the tires (which are new). He told me that with the money he earns from selling everything, he wants to buy a new cell phone--specifically, the Samsung S7.

Personally, I think spending more than $200 on a cell is a waste of money, especially with little ones in the house and how quickly the manufacturer's pop out a new version. But he's adamant on buying a new phone. And yet, he wants to plan a vacation to Disney World for the kids' birthdays in Oct. I think that money would be better put to use in saving for the birthday trip or even to cushion our savings account. He just spent $10K in buying a new truck for his job, so now to spend another $700+ on a cell phone that he'll be forced to change in a year?

Finances and budgets have always been an issue with him. He doesn't understand the importance of maintaining a budget, nor does he understand household accounting. And I'm tired of having the same discussion with him.
Added (1). I barely see our kids as it is with my current work schedule, but it's getting to the point where I may have to take on a second job or ask for OT to just to pay everything off. If we had little to no debt (i.e. Only 1 credit card), it wouldn't be much of a big deal.

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