Copy values from XML element to create a new element with combined new value

I have this XML with multiple products and I want to add a new element with the values of other elements. I want to add a new element to each titled . This should include the values of ProductOption, PurchaseOption, Quantity. Example should look like <sku>price-each-an-order-250-499</sku>.
I am open to different technologies, like command line sed, bash etc.., php, python, javascript.

Input XML

<Catalog>
    <Product>
        <Number>82508</Number>
        <Title>Product Title</Title>
        <Description>description</Description>
        <Variations>
            <!-- An Order; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>250-499</Quantity>
                <MinQuantity>250</MinQuantity>
                <MaxQuantity>499</MaxQuantity>
                <Price>1.09</Price>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>500-999</Quantity>
                <MinQuantity>500</MinQuantity>
                <MaxQuantity>999</MaxQuantity>
                <Price>0.95</Price>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>1000-2499</Quantity>
                <MinQuantity>1000</MinQuantity>
                <MaxQuantity>2499</MaxQuantity>
                <Price>0.93</Price>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>2500-4999</Quantity>
                <MinQuantity>2500</MinQuantity>
                <MaxQuantity>4999</MaxQuantity>
                <Price>0.87</Price>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>5000</Quantity>
                <MinQuantity>5000</MinQuantity>
                <MaxQuantity></MaxQuantity>
                <Price>0.84</Price>
            </Variation>
            <!-- A Quote; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>A Quote</PurchaseOption>
                <Quantity></Quantity>
                <MinQuantity></MinQuantity>
                <MaxQuantity></MaxQuantity>
                <Price>0.00</Price>
            </Variation>
            <!-- A Sample; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>A Sample</PurchaseOption>
                <Quantity>1</Quantity>
                <MinQuantity>1</MinQuantity>
                <MaxQuantity>1</MaxQuantity>
                <Price>0.00</Price>
            </Variation>
        </Variations>
    </Product>
</Catalog>

Expected Output

<Catalog>
    <Product>
        <Number>82508</Number>
        <Title>Product Title</Title>
        <Description>description</Description>
        <Variations>
            <!-- An Order; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>250-499</Quantity>
                <MinQuantity>250</MinQuantity>
                <MaxQuantity>499</MaxQuantity>
                <Price>1.09</Price>
                <Sku>price-each-an-order-250-499</sku>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>500-999</Quantity>
                <MinQuantity>500</MinQuantity>
                <MaxQuantity>999</MaxQuantity>
                <Price>0.95</Price>
                <Sku>price-each-an-order-500-999</sku>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>1000-2499</Quantity>
                <MinQuantity>1000</MinQuantity>
                <MaxQuantity>2499</MaxQuantity>
                <Price>0.93</Price>
                <Sku>price-each-an-order-1000-2499</sku>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>2500-4999</Quantity>
                <MinQuantity>2500</MinQuantity>
                <MaxQuantity>4999</MaxQuantity>
                <Price>0.87</Price>
                <Sku>price-each-an-order-2500-4999</sku>
            </Variation>
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>An Order</PurchaseOption>
                <Quantity>5000</Quantity>
                <MinQuantity>5000</MinQuantity>
                <MaxQuantity></MaxQuantity>
                <Price>0.84</Price>
                <Sku>price-each-an-order-5000</sku>
            </Variation>
            <!-- A Quote; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>A Quote</PurchaseOption>
                <Quantity></Quantity>
                <MinQuantity></MinQuantity>
                <MaxQuantity></MaxQuantity>
                <Price>0.00</Price>
                <Sku>price-each-a-quote</sku>
            </Variation>
            <!-- A Sample; no imprint -->
            <Variation>
                <ProductOption>Price Each</ProductOption>
                <PurchaseOption>A Sample</PurchaseOption>
                <Quantity>1</Quantity>
                <MinQuantity>1</MinQuantity>
                <MaxQuantity>1</MaxQuantity>
                <Price>0.00</Price>
                <Sku>price-each-a-sample-1</sku>
            </Variation>
        </Variations>
    </Product>
</Catalog>

Not sure what to use to accomplish this. Any examples or tutorials would be helpful.