I have 2 Reference 405 amplifiers I have owned since new (one from around 1995, other, a 405s, from 1997), and have had them fixed for some problems, but they keep going just fine. I would personally have no problem buying a used 405 or 405s and if it developed a problem, have it repaired. They run very reliably and are worth fixing. One of mine is now in storage, the other has been in continuous service since being installed in my truck back in the 90's.
Why do you have to get a "new" one?
If you really want one new, the only way I have found new old stock is to save an eBay search and be willing to wait years to find it, which I have occasionally done. But you could wait a long time to find one that is brand new.
