Floral Expressions Rents Vases.
I believe Ed's Events will also rent vases to you.
I bought my vases second hand off of a lady on weddingbells.ca There is a forum for people in and around the ottawa area and they sometimes sell off their used wedding thins in the "swap shop".
Actualy I think any decoraters will rent them to you...
Click on each tool to see a sample.