Portable belt sanders are common among avid DIY enthusiasts, as they have a multitude of uses around the shop and your home. But the typical standalone edge sanders can run north of $1000. But with a little work you can transform your handheld belt sander into a usable edge sander.
Keep your cash and follow YouTube user Savvas Papasavva's lead as he builds a benchtop jig to turn his belt sander into an impromptu edge sander. You can see more detailed instructions here -- or check out one of many other similar guides on the web.
Of course, you could always just turn your belt sander on its side and clamp it down... but this is a safer option.
Mini Edge Sander - Belt Sander Stand [Miscellaneous Productions]