Interesting idea. Would that detail really be useful?
I think if the reason you want to keep a copy of the transaction receipt is for taxes or some other legal reason, you’re going to need the hard copy anyway. Since you’d already be keeping the paper receipt, what is the value of keeping a scanned image if it? CalendarBudget will already hold the correct amount.
I had thought originally to put some space to record some details for each transaction. My thought was it would be a textarea, where you could enter free text about any details you want. I ended up not implementing it, because it seemed overkill for the average user and I wanted to keep the edit dialog clean and not cluttered with extra fields that most people won’t use.
I’m not sure its really worth it. It you would have to store lots of different documents of various sizes. Plus this actually goes against your desire to not have truely identifying data on the site. if you have someone post up images of their mortgage or check images, all those could be expoitable if they were illegally accessed. I think if users want to store paper items they deem as valuable, they should get a safety deposit box to store the original.