The only way for you to get a high quality $300 waterproof bino is to buy a porro prism design. Roof prisms are cool and very fashionable but because of their more complex optics and body design they cost 2 -3 times more than optically equivalent porros. It's like a law of nature, there's no gettin' around it.
Look at it this way. I've got a ten year old pair of Nikon 7x50 Naturalist XL RC (camo rubber coated). They're clear as a bell and I love them dearly. Their depth of field is awesome, focus them once and forget it, they stay focused from 30 feet to infinity (I've never seen a roof at any price come close). It's a huge benefit when hunting. Great dawn/dusk glass, heck, you can even discern useful images at night in bright moonlit. They set me back around $280 IIRC. I've compared them side-by-side to high end roofs and optically they're equivalent to roof glass costing $500 to $750.
So what's the trade off? Porro prisms are bigger, bulkier, and (usually) heavier. That's the down side. I bought a good neck strap and moved on.
The Nikon Superior E 8x32, though not waterproof, is considered by many the most optically perfect binocular made. They're a porro prism design and cost around $600. It
might be possible to make a roof prism to equal them but they'd be so friggin' expensive I don't think anyone's even tried.
Forget the Nikon Monarchs. Optically they're worse than many porro prism costing around a hundred bucks. Check them out side-by-side with a $110 pair of Nikon 7x40 Action porros and tell me which one is clearer. Dollar-for-dollar I think Nikon makes the best binos on the market, but IMO the entire Monarch line is just awful.
Getting back to your original question. Check out some of these sub $300 waterproof porros: Fujinon BFL 8x42, Nikon Sports/Marine 7x50, and the Bausch & Lomb Discoverer 8x42 Porro. For around $500 there's the Swarovski Classic 7x42 MGA. Optically it's probably the best glass Swaro makes. Any of these will easily out class roofs costing twice as much.
Pentax DCF WP 8x42 is definitely the cream of the crop of the sub $400 waterproof roofs. The Bausch & Lomb Discoverer 7x42 is another good roof bargain and closer to $300.
Here's a couple of more links to get you going.....
Better View Desired
Eagle Optics
Both sites are packed with a ton of bino info. -- Kernel