http://www.universalcycles.com/shopp...s.php?id=25214
These guys have 280, 282,290,292mm spokes and sell individually I believe. You will be fine will a 1mm difference in spoke length from what is ideal. I hope you are matching these to other Aerolite spokes as mixing spoke models/manufacturers is not a good idea.
PS- Id go up 1 mm rather than down. IE get 4 each of 182 and 192mm