What operating system are you running. Fontforge is a free open source project that is viable. It is what I used until I was sure I was ready to spend the money on font studio pro.
You could download the trial version of FontLab TypeTool 3. The OT features can be build with the AFDKO (Adobe Devolopment Kit for OpenType). And if you like TypeTool, you can upgrade to FontLab Studio.