Substrate suggestions

I've decided to pull my gravel out, and replace it with sandbasting 
grit, after finding out my gravel is causing my pH to raise to 7.6. 

Any suggestions on a laterite I should us.  I could spend lots of 
money on dupla, but with having a 135 gallon tank this would cost 
alot. Bad!

I've heard of using "red art clay", vermiliate (sp?), peat?, and a 
half dozen other combinations.  What do you use, has it worked for 
you, and what would you recommend.  I am willing to spend the money 
for dupla's laterite if it is far superior to any other option.

Let me know.  Thanks in advance-  Matt