Creating covers for IngramSpark is more difficult and time consuming than doing so for KDP. That’s why the price is $45.
If you wish to publish through IngramSpark, make sure you note that in your Paperback Add-On Request form (my default is KDP). I’ll need to download an IS template set to your specifications (your ISBN and exact page count are required to create the template), or you could create the template yourself from this site and send me the PDF copy. Your ISBN and barcode will come with your finalized IS cover.