Грешката ви е в сметките при изчисляването на цената на компонентите. Прикачвам ви поправеното решение:

function shopping(budget, videoCardCount, processorsCount, ramMemoryCount) {
    arguments = [...arguments].map(arg => +arg);
    const calcDiscountedPricePerItem = (price, percentage) => price - price * (1 - percentage);

    const gpuPrice = 250;
    const cpuPricePercentage = 0.35;
    const ramPricePercentage = 0.1;
    const gpuPercentageDiscount = 0.15;

    const totalGpuPrice = videoCardCount * gpuPrice;
    const totalCpuPrice = processorsCount * calcDiscountedPricePerItem(totalGpuPrice, cpuPricePercentage);
    const totalRamPrice = ramMemoryCount * calcDiscountedPricePerItem(totalGpuPrice, ramPricePercentage);

    let totalSum = totalGpuPrice + totalCpuPrice + totalRamPrice;

    if (videoCardCount > processorsCount) {
        totalSum *= 1 - gpuPercentageDiscount;
    }

    const cost = budget - totalSum;

    if (cost >= 0) {
        console.log(`You have ${cost.toFixed(2)} leva left!`);
    } else {
        console.log(`Not enough money! You need ${(-cost).toFixed(2)} leva more!`);
    }
}