I could definitely "use an extra 50 or 100 grand". I've has an attorney send a cease&desist letter, and recieved a terse response. It's litigate, not negotiate. But litigation is a complicated decision, and what's right, or wrong, isn't the only contributing factor. The parent corporation of the offending company has annual revenues of $50 billion. Bringing a lawsuit could cost me $200,000, or more. What's the risk/benefit ratio?
As my father told me, life is hard.
Sending you a terse response is cheap for them. Big companies ignore patents and trademarks regularly when they know the intimidation factor is high or the cost of settling out of court is a small fraction of their profits. Take a cut of their money.