if u are not oc the duron, it should be cool enough to use a low volume fan like 80 mm panaflo. My suggestion is:
1. use some heat glue gun to make the new fan to stick to the heat sink, or
2. like me, use a used CDROM (or may be more to make a tunnel), cut it to right size with holes for 60mm and holes for 80mm, cut the middle a opening and find some screws that fit, or
3. use some thing to tie the fan to the heat sink (like those that tie up your bread),
4. use a 80mm grill and put it off-side (rotate may be 45 degree) and see if u can screw the grill to the heat sink in between the grill, if yes, then your 80mm fan can set on top it.
....
be creative, many option....
and yes you can buy a new one and hope it is quiet....
34 dba for Doctor look loud to me on paper... look for below 30