If it isn't that expensive and not worth it to you to go to the trouble of keeping the receipt, why are you going through so much trouble to get it repaired/replaced, and making such a big deal out of every cent not being accounted for? If you want that type of treatment, keep the receipt! But even if you had the receipt, I still would not think you should expect the entire amount, plus tax, plus shipping, plus whatever else you are asking for. If you had the receipt, which you deemed unimportant, you'd get more. That is a fact. They are under no obligation to offer you anything, do you not see that? Do you really think that they should go by no proof and offer you every penny you ever contemplated spending on that not-expensive-enough-to-keep-the-receipt piece of luggage?
Just because I don't think a $320 luggage is expensive and just becasue I did not keep the recipet does not mean that I should not go through the trouble when someone else broke my luggage. I hope this is clear. It's a matter of principles.
And as others have said, market value minus depreciation seems to be the widely accepted method. In this case, the market value is clearly available - $320 plus applicable tax. Hence, it is not a good practice to deduct an additional 10% for not having the reciept, clear?
How about you use the example of a car. A car is worth less than you paid for it the minute you drive it off the lot. Is the entire value of a car replaced if damaged?
Yes, in certain cases and no in others. In your example of a car, it mostly depend on your auto insurance contract. For example, if you have a lease car, you will most definiltey have an insurance contract that will reimbuse you FULL MSRP if there is a "total lost" of the car. This is because the leasing company would need this full amount.
If you own the car yourself, it will be depreciated accordingly, but this is entirely because without depreciation, car owners would have the "intention" to get into accident and get a total lost to "gain." (the gain being the difference between full MSRP vs true value of car). Anyway, this is what a "moral hazard" is defined in insurance terms.
In other insurance, where you don't have moral hazard, the insurance will almost always be full REPLACEMENT value. For example, your household contents insurance - if your house get robbed, your household contents insurance will pay you back items lost at replacement value, not depreciated. And if your house gets burned down, the homeowner insurance will also pay replacement value which is often more than the original price (well, except in today's world of housing crash, it might be different).
And if you have any sort of insurance for any particular things - for example, jewlery, musical instruments, etc. It will also be replacement cost, not original value.
Anyway, this is probably more than what you want to know.
What if they no longer make that car?
Then, there will be a third party to come up with an appraised value of the item/car/whatever.