This is one reason to keep patents provisional as long as possible - you get the investors to cover the capital outlay of executing the patent.

If you launch into the WIPO "International Patent" process, for an upfront cost (US$5k or so - varies a lot on circumstances) you can extend the process by quite a bit - up to 18 months iirc. My bus partner wrote a blog on this after we'd done rounds of meetings with attorneys : http://www.jodoro.com/2008/09/patent-discussions.html