I just bought a used BJ4 and with the exception of a few parts that you have to order from JConcepts (shock towers, chassis, etc), many of the parts on the original BJ4 (non-world's edition) are either from Losi or the Associated B4, so it's pretty easy to find parts for. Just my thought, but I ran it for the first time in a race 2 days after I received it, and took some spectacular crashes and didn't break anything. It held up better than my Revo!
Food for thought...
Losi XXX-T CR * Traxxas Revo Tekno Brushless Conversion * Losi 8ight 2.0 * Losi 8ight-E 2.0 * Corally RDX * HPI Blitz * Tamiya F104 V2 Pro * Associated TC 6.2