infinityfreenom

foreach ($arBlocks as $IBLOCK_ID) {
  $multiplier = getPriceMultiplierByBlock($IBLOCK_ID);
  $newPrice = $price * $multiplier;
  // сохраняйте
}

function getPriceMultiplierByBlock($blockId) {
  $multipliers = [
    2 => 1.30,
    8 => 1.30,
    9 => 1.20,
    43 => 1.25,
    44 => 1.20,
    45 => 1.10,
    99 => 1.10,
    // ...
  ];
  return isset($multipliers[$blockId])
    ? $multipliers[$blockId]
    : 1; // если множитель не указан - единица
}

SELECT COUNT(*) FROM mytable 
WHERE myfun( field ) IN ('str1', 'str2', 'str3');

SELECT COUNT(*) FROM mytable 
WHERE field IN (myrevfunc('str1'), myrevfunc('str2'), myrevfunc('str2'));