your motherboard is AGP x4/x8 an that would really require an outdated GPU which really wouldn't be cost effective.
BUT to try to find something for you:
VisionTek 400518 Radeon HD 3650 1GB DDR2 AGP $54.99http://www.newegg.com/Product/Product.aspx?Item=N82E16814129235
most anything else is less than 1 Gb of memory
a day later and a dollar short