Not a bad solution!

My only suggestion would be to avoid using an array if possible.

Pushing all those numbers is unnecessarily expensive!

We basically did the same thing though:

function maximumToys(prices, k) {
        let sum = 0;
        let sorter = prices.sort((a, b) => a - b);
        let counter = 0

        for (var i = 0; i < sorter.length; i++){
                if (sorter[i] < k){
                    sum += sorter[i]
                    if (sum <= k){
                        counter++
                    }
                }
        }
        console.log(counter)
}