I worked out what is in my rod holdall alone, and know that £1500 for rods and reels is about right for me on purchase price, although obviously I no longer have receipt. I do have pictures of my gear on the bank in use, but I reckon like everyone else things get added as you update or buy additional items.
I keep most receipts on my purchases for a year as habit, I have a kitchen drawer full of them, both fishing tackle and household items, then every now and again go through it and bin older out of guarantee receipts.