Your Toyota speaker harnesses you linked are great. They're what I've used when I went aftermarket fronts so I can go back to stock if needed.
Since I have free prime, I bought them off amazon:
As for deadner, I went with Fatmat Mega Mat off ebay. It was the most economical at the time, I spit a 100sq/ft roll with a buddy. With 50 sq/ft I've done in/outer front door skins on 2 cars now and still have plenty left over to spot apply if needed. So you could split that $250 roll 4 ways with some buddies and only be out $62.50 for mat.