Since the cooling solution came with the motherboard, I would suggest contacting the motherboard manufacturer for recommendations.
Keep in mind that cooling solutions for mobile processors like the i5-2520M are to be provided by the motherboard or system manufacturer, not by the processor manufacturer.
Some Socket G1 heatsinks may fit socket G2 mini-ITX boards. I bought CoolJag BUF-A, and it works fine in my Jetway socket G1, and Supemicro socket G2 motherboards. I can't comment on how loud it is, because I never really paid attention. I bought it because Jetway socket G1 board came with pretty crappy heatsink, that din't cover full surface of the die.