I just found out how frustrating this can be! Item sold Tuesday ~8pm EST and was paid for immediately. It wasn't in my ended sales Wednesday, and Thursday morning the entire site was inaccessible for me. Thursday night at 11:30pm I checked and the item was there, but insurance couldn't be purchased because it had been more than 48 hours since payment was made.
I know I could email Auctiva and have them purchase the insurance, but with the move I thought they might be preoccupied. So I purchase insurance elsewhere.
The 2-day limit is difficult for me as is because I don't usually do my paperwork until I am ready to ship and I don't usually ship next day. Add in some late-night purchases and I'd miss my chance to purchase insurance on a lot of things. Sometimes life takes us away from the computer for a day, ya know?
If the reasoning for the limit is so we don't purchase on a delivered item... well, in rare instances, I've had a buyer pay for something in the morning, express-mail it that day, and they have it the next day.
If you want us to use the insurance through Auctiva, make it easier to purchase it and give a broader time frame. U-pic themselves don't seem to have a limit imposed on how long after payment you can purchase insurance.