When you make the decision to lace a new rim to your hub there is a complex formula used to determine spoke length for both inner and outer spokes. The formula requires lots of information about your hub like distance between spoke flanges, Hub diameter from spoke hole center to spoke hole center, distance between spoke holes on center etc. This formula also requires the effective rim diameter which must be measured while you have the rim in hand to be sure. It can be done but most people seem to just call Buchanan and ask them, I understand if you call them up you can give them the information on your Hub type and the rim you plan to use and they will calculate spoke length in order to make and sell you their spokes. I'm not advocating that you buy one of their rims or their spokes, I have done the research and figured it out for myself based on parts that I have on hand and I have been able to accurately calculate spoke length myself for my own use. There are some aluminum rims available on eBay from Southeast Asian countries, I took the time to research these rims, they have the name racingboy on them in the eBay photos, if you look up racing boy, they seem to be a pretty huge company with a long history. They've got distributors over much of the world including Bermuda and South Africa not just in the Pacific area. So it seems like about two-thirds of the world is riding on their parts. If you check out web forums looking for information on these wheels you won't find much, just a lot of narrow-minded people who won't trust their life two so-called cheap Chinese crap. But if you look a little deeper and read project threads on many many forums you will find that several people have used these aluminum rims, racing boy brand, and had a great deal of success, no failure seem to be reported anywhere and if you ask the people that have bought these wheels they'll tell you that they're high quality. Some of the eBay sellers also have stainless spokes available, people that have bought those report that at the head end of the spoke, the bend is dissimilar to stock spokes, and it fits slightly differently at the head end where it meets The Hub. Once tightened and trued though, they seem to work just fine and have as long of a service life as you would expect. If I remember correctly the only complaint was that some of the brightly colored powder coated rims would fade in the sunlight eventually.
This is a very confusing area that you're getting into, that's why most people call Buchanan, write the big stinky check and let them do the work and thinking for them, Buchanan has a great reputation and their products are all top notch, but this can honestly be done buy a do-it-yourselfer without them.
Maybe someone from New Zealand, Australia, Malaysia or in that general part of the globe can chime in on these.
I had sent a message to an eBay seller about the racing boy brand rims in aluminum, 17" diameter, 2.5" and 3.5" widths, spoke holes drilled for drum brake hubs on both, and stainless spokes for front and rear, he couldn't calculate spoke length for me but would use spoke lengths I dictate. The price he gave me for both front and rear rims in aluminum and spoke sets in stainless was around $320US including shipping to the northeast USA.