quarter of a million words available, it's good to know that people are still creating new ones.
Approaching manufacturers. We think you'll have a hard time convincing manufacturers to buy rights to your word. All the made-up words that we've seen used as trademarks -- for example, Nerf, Kodak, Viagra, and Kleenex -- are usually associated with new products. (Actually, Nerf is an acronym for Non-Expanding Recreational Foam.) So unless you also have some proprietary product ideas to go with your new word, we think you're headed in the same uphill direction as Sisyphus.
Can you claim rights under an intent to use application? A manufacturer is going to want an assurance that you have rights to the mark. We know you'd like to use the word as a mark but do you actually have a bona fide intent to use the word as a mark? As this case and others have shown, without actual evidence of your intent (more than a desire to profit), your claims over the word may be subject to challenge. Here's more on the subject.
Can you sell what you have? Sure, you can sell the domain names anytime, no problem. But we don't think anyone would want to pay for the "trademark rights" because you won't have any rights until the word becomes a trademark. That occurs after the mark has been used in commerce. We think this is one of those cart-before-the-horse situations and suggest you could save money on trademark fees by reading up on some of Nolo's excellent trademark articles.