JL Audio Fathom Owners and Looking to own One

I don't think anyone repairs plate amps. It's hard to say whether $1k is an unreasonable price for replacing that particular amp without more insight into the cost structure at JL. It wouldn't be too shocking to me to assign a quarter to a third of the cost of the new product to the amp, so - if the sub was app $2k MSRP - and, given the labor involved in such a repair, $1k might well be in the expected zip code for the job.

It sucks, but I'm not at all sure that they're being unreasonable with you. OTOH, I can't be sure that they're not being unreasonable. Either way, you can buy a pair of excellent subs from SVS, Rythmik, or Hsu for app $1500, so it might make more sense to just move on.

A friend of mine looking to build a subwoofer is looking at a 750W amplifier for his subwoofer and it costs about 800 bucks. If the item is out of warranty and you had to pay over a thousand for the 1500W amp in the JL subwoofer, it is IMHO not entirely unexpected.

In some respects, it is like if you buy an old Ferrari 360 for cheap money and baulk at the maintenance cost of running a Ferrari.