Probably low, since there's already at least one low priced service (zooomr) that has no individual filesize limit. Prices of hard disks have been dropping precipitously, so I think there's an expectation out there that the same cost for online services should happen (gmail's steadily increasing quota also reinforces that). I realize those expectations are probably unrealistic.

In terms of bandwidth, a flickr-like display that shows a smaller size by default mitigates that. It's the convenience of uploading a full-size file and getting it resized to multiple sizes (and the full size is there for those who want to see it).