http://www.reddit.com/r/ffxiv/commen..._that_we_know/

Summary:

From this we can gather a few things.

• Gear will SB 19 levels below the mobs' level and 18 levels above
• Bonding 'peaks' at exactly 10 levels below the mob
• Bonding 15-8 levels below the mob gives a huge increase to SB rate
• Overall bonding seems to have gotten a nice boost until you bond items 8 levels over the mob
TLDR: Research the proper iLVL ranges, SB in the correct content, and you will actually see a significant increase in overall SB rate / materia yielded. And particularly relevant to this thread:

So what does this mean for those worrying over novus? I'd advise against buying materia atm as most servers seen a jump in price due to speculation over the new rates. However looking at these numbers, the supply of materia I's and II's will almost double while the supply of III's (and by virtue IV's) will see around a 30% increase if your server's market is healthy. So wait a bit as chances are prices will drop lower than they were pre-patch as the supply starts kicking-in
The exact percentages are tough to pin down, but I agree with his general conclusion.