Check ebay. You can find some pretty good deals on there. I've seen quadruple rate piggyback elka's go for $400. Also if you can afford a round housing +3'' swingarm, thats the way to go. It makes adjusting the chain so much easier.
The round housing swingarms are like the honda swingarms. You undo 4 bolts in the rear and rotate the bearing carrier to adjust the chain. With the stock yamaha style carrier, you have to make sure you keep the carrier straight when your adjusting it. You can also get them in different lengths. If you look at the back of my swingarm, you can see how its different from a stock one
Snyder motorsports and asr make some good ones. You don't have to modify anything, simple bolt on. Burgards are nice as well, but you'll have to ream the spindles if you go that route. Whatever you decide, I'd go as wide as possible, at least +3+1's. I'd do a hydro conversion first though. Not sure if you can get extended cables for the front?
Correct, +3+1 means +3'' wider per side and +1'' forward. New on ebay you can get a set of +3+1 asr a-arms for about $400. Sometimes you can find used ones for around $200-$300. I picked up my a-arms used on ebay for $265 shipped to my door
well man i dont race but i did get some good deals on my suspension and stuff.... i got my +3+1a=arms used for like 280 there asrs... works front shocks for like 160 used and the rear a trx 250r but with wheel spacers..... and it sits just as wide as a stock z400 maybe a tad wider