Cliparts (WMF vector files)

My company is developing an on line application for T-shirts designing. We need clip arts that we can implement in our application for the usage of our customers. We need an initial quantity of? 100-200 clip arts and it is more than likely that we'll need more clip arts in the future. The clip arts should be in various topics. The clip arts file format should be WMF or SWF in RGB colors.