Sigh.
A trademark for a common item (like a T-shirt or a voltmeter) seems to cost about $350 through the USPTO, if you do it yourself and your goods are listed in their directory.
If your goods are oddball (like glass or woolen nonorientable manifolds) then you have to use a more expensive system which starts at $450 and escalates depending on how many different types of goods you're trademarking.
We had a tricky trademark submission recently and we were provided with a free attorney who was spectacular and very easy to work with. Your assessment matched my experience.
I'm sorry Cliff: the system sucks because there's a lot of edge case handling when they're dealing with millions of vendors selling literal hundreds of millions of SKUs.
Many of them autogenerated programmatically like "I love X" shirts, and X = some dictionary list; or bots built to crosslist Target/Walmart product over to Amazon etc. for arbitrage etc.
I hope someone from Amazon has reached out to you Cliff - my wife gifted my FIL one of your klein bottles and it's been an absolute delight going through the purchasing experience with you. Thank you for the joy you bring to us!
The system sucks because the income gained through dealing with millions of vendors selling literally hundreds of millions of SKUs is channelled into Amazon's profits, rather than people or systems to deal with the resulting problems.
It's actually worse I think: Amazon demands the people and systems to be better-on-metrics over time -- dealing with Seller Support is just a huge nightmare these days as a seller.