Personally, I have only seen conferences which require **every** paper to be presented on-site. Most conferences explicitely state that paper will not be published in the online proceedings, if the authors does not present his/her paper. If this is not stated on the conference's website, please write to the committee.

However, I recommend you to find a different solution. Discussing a paper at a conference is a very important part of your scientific career since you get in contact with other researchers. If you encounter financial difficulties, you can write to the committee and ask politely for a waifer or reduction of the fee.