Okay, so they are using 47 ohm resistors that look like 2W metal film, but they could be 1W. Radioshack.com has a 5W 47 ohm resistor for $.34 each. (SKU 900-0937)
http://www.radioshack.com/searchsku.asp?find=900-0937
Unfortunately, this value is not stocked in their stores and must be ordered online, but that's the way Radio Shack has become lately. More appliances, less parts.
I'm sure if you had an Electronics Surplus store near you, you could find them there.
The problem you run into is that the 47 ohm resistor is adequate for dropping the speed of one .25A fan. If you put two of those fans in parallel, then 47 ohms is too much. Worse even yet for that .9A Delta. Likewise the new fans at .37A. The more current a fan or combination of fans draws, the less resistance you need to drop the voltage reaching that fan(s) to the same point. You don't want to slow them down too much or they become ineffective.
Lets look at ratios for a second. If 47 ohm is ideal at .25A, then (.25A/.37A)*47= 32 ohms for the new Sunon fans. I'm going to disregard that Delta fan because it is inappropriate for a case fan. 32 ohms is not a standard resistor value, but 30 and 33 are. Radioshack.com has the 33 ohm (SKU 900-0933) for $.34 each also.
http://www.radioshack.com/searchsku.asp?find=900-0933
Personally, I think all those 80mm fans you are planning will be sufficient for adequate case ventilation. In searching for information on the Lian Li PC70 last night, I did stumble across a case mod to use 92mm fans in place of the intake 80mm ones. That's what I would use. Yes, it involves nibbling out the holes on your nice (expensive) case, but if approached with some forethought and performed with care, it will not detract from the appearance. I would think that using a pair of 92x32mm Sanyo Denki Mini Ace 32
http://2cooltek.safeshopper.com/27/198.htm?708 fans on the front intake and four of the stock fans on the exhaust, along with your PSU fan would yield an excellent setup with tolerable noise. In that case, you would control the two S.D. fans speed to yield a slight positive pressure. The Sanyo Denki Mini Ace 32 is in my honest opinion the best fan for case cooling ever made and I don't make such absolute statements very often.
Hoot