dextran sulfate-- a cheaper source??

[Michael Man]

 	I use dextran sulfate in my hybridization solution.  It gives me very 
good results, but it is too expensive, $732 per 500 gms from Sigma.  Does 
anyone know a cheaper place to go?  Thanks for your help.
	Also I will be very grateful if you can suggest an alternative way 
to prepare prehyb. and hyb. solution.  I use GeneScreen transfer membrane and
UV-crosslink RNA. 


Michael
mman at molbio.cbs.umn.edu