I've worked with these kinds of fishing projects before. I am a holder of a US patent on a weedless hook design. I also had a lure on the market for awhile with my name on it. Since I don't know the exact configuration of your device, I can only speak in general. I'm going to assume based on your target price of $.25 a piece, that you're thinking of production and not just making a few for your own personal use:
1. If this is something that you hope to patent and market commercially, you need to know your target audience and the volume involved. If you're thinking of small scale 'garage' production, you'll need a product that can sell for a premium amount, and know that your target audience will pay that amount. If not, you're still in the imaginary stage, which is fine.
2> If you have a distinct design and you're planning on selling volumes commercially, then you're in the prototype stage. You don't need to make the final product, only a functional facsimile. Regular solder may work for this. Take any of the black nickel finished hooks out of Japan like Owner or Gamakatsu. The black nickel is laid on top of a copper undercoat chemically bonded to the underlying steel. You can finely sand the nickel off to get to the copper undercoat, which can then be soldered using regular lead solder. Consider a piece of brass for your metal plate, which can also be lead-soldered. Now you can prototype to your heart's content without becoming too elaborate, costly, or time consuming.
Once you have your design down, then you'll need to patent it. Once patented, you'll then need to license or sell outright to an established lure/tackle manufacturer. There's a good number of smaller premium producers today that are easy to approach with such ideas. Educate yourself on business though before settling on numbers--it's easy to get burned.
Or....
If you want to produce them yourself, you'll probably need to outsource production. If it's a modified hook, then the hook companies I mentioned would be interested. Even Eagle Claw USA will do contract work. If it's a lure, then you'll probably need it produced in China or Mexico. There are a few US mfrs that could do contract metal lure work for you, but the price will be higher. In this latter case, BE SURE IT'S FOR THE BASS FISHING MARKET. That's the best easiest market for quick turn around at premium prices. Unless you're making spinners, spoons or jigs for other species, but they don't sell for premium prices.
There's a whole lot more to it but that's a start. If you're a fisherman, you know everyone's a tinkerer and everyone's an inventor. For every viable product, there's 10,000 that are nonviable for a slew of different reasons. I can't comment any further without more specifics.