Sending students for conference presentation with no additional funding
It may be possible to make some of the conference cheaper overall. To give an example some IEEE conferences registration fees are very expensive, this can't be avoided. The last one I attended was also in an expensive hotel. It may be possible to get other accommodation further away and travel in. They may ask for student helpers as well, which could add extra discounts. Early booking may give early bird registration fees as well. The flights, which I assume are required equally might be cheaper in advance.