Holy S#/+!! You must be the ultimate DIYer!! Wouldn't you rather buy 8-$6.00 Vishay/Dale Power resistor. Vishay makes some of the best, if not the best, resistors in the world. Dale is no slouch either. It maybe safer if you leave the component level construction to the pro's.
I read once that Audio Note wasn't satisfied with the sound quality of components for audio, so they began to make handmade wire-wound resistors, hand-wound silver wire transformers and oil capacitors for their amps. But...that's Audio Note, who has charged way over $100,000 for a tube amp. I'm not talkin about the kits either, I mean the ones made in Japan. Anyway...
I don't mean to sound skeptical, but...that's a tough order.
If you can make a resistor that bests commercially available ones at any cost, LET US KNOW!!
My mistake. You can get 50 watt Vishay/Dale resistors for $3.70 each. $2.78 for 10 or more of the same value. You could paralle or series a few to dissapate the power. You can get these from Mouser Electronics. Digi-Key has 225 watters, but they are not aluminum housed and I didn't see 7.5 or 8 OHM. They were over $20 each.
The 1 OHM resistors only need to be 1/8 the wattage rating. These would fit in nicely, but I couldn't find 250W ones for you, sorry!
Hi - for what it's worth, it may be worth checking out http://www.rhopoint.co.uk/components/powerp.htm - neat looking range of (designed for large flat surface mount to heatsink) power resistors. No more info - these may be no good for SOZ, but caught my eye when surfing for NTC anti-surge devices (see same page) - I'm building Zen Revised not SOZ.
How's this for an inexpensive idea: Heater elements from clothes dryers. I seem to recall measuring one once upon a time at 3 ohms or thereabouts. The wire (Nichrome?) was suspended on an open frame in fairly widely spaced coils, surely wide enough that any inductance would be minimal. Screw connectors were provided at the base, along with mounting holes. Dead dryers (i.e. burned out motors, but intact heaters) aren't hard to find, so the elements would be free for no more than the investment of a few minutes with a 1/4" nut driver and a screw driver. How such a resistive element might sound, I have no idea, but it would be cheaper than the Dale load resistors.
Making good resistors is pretty easy. There are no non-inductive resistors, but even the low inductance winding techniques aren't difficult. IMO, the biggest problem is that most resistance wire can't be soldered. You have to rig up a spot welder to attach it. Constantan can be soldered and makes a good resistor if you don't mind a bit of thermal emf at the junctions (it's thermocouple wire). Manganin is great- can be soldered and has near zero thermal emf, but it tends to be expensive and a bit low in resistance. So, choose your wire and your attachment method. Next, find a ceramic tube or flat wafer to wind on. I'd probably coat it with a hi temp silicone. Projects like this are fun and educational, but you'll likely spend more than if you bought a commercial part.