Not familiar with the laws concerning plating in your area, but I would think us in Cali have it the hardest.
A few of the places I look:
Facebook, search for groups for the bikes you're looking for and join the group to get updates and find people who may be able to help locate a bike.
Craigslist, need to search nationwide.
Aprilia forum, classifieds and also the RS125 forum.
cycle trader, nationwide search
Good luck in your hunt!
Jenius Biker Blog
Current FTR, Metro, RS250³, V7, RC39, TT
, Bangkok, 85 ADV
Past: Newd, Zuma, Diavel, Zero, Grom, M696, GTS300, KLR650,SC1000s, CeRbi, SPR, 959 Corse, CB300R, SRMotard, Versys, Typhoon, NCXD, RC390², Madass, PW50, KTM BR 65, Aprilia BR50, Aprilia RS125², DRD, WR250X, Derbi SM⁷, Aprilia RS50¹⁰, Derbi GPR³, Aprilia RS250², Mito², NSR50², NS50, HRC RS125, HRC RS80, YSR63 (1st 2stroke!), FZ600, KLR250(1st Bike!)