<?php

$updateFinal = array(
    array(
            'sku' => 14110,
            'price' => 35,
            'fulfillment-channel' => 'amazon'
    ),

    array(
            'sku' => 14486,
           'price' => 48.16,
           'fulfillment-channel' => 'amazon'
       ),

   array(
           'sku' => 14430,
            'price' => 46,
            'fulfillment-channel' => 'amazon'
        ),

    array(
            'sku' => 15124,
            'price' => 25.8,
            'fulfillment-channel' => 'amazon'
        ),
    );

$handle = fopen("prices.txt", 'w+');
$keys = array_keys($updateFinal[0]);
fputcsv($handle,$keys,"\t");
foreach ($updateFinal as $row) {
    fputcsv($handle, $row, "\t");
}
fclose($handle);