The Seiko SRP307 (aka Black Monster) is a revamp of the original Seiko "Monster" models. The updates though subtle may just be enough to make this the best Automatic Diver's Watch to get in it's price range. I bought mine online for $200 about four years ago and have been loving it ever since.
First a quick discussion of the original Seiko Monster watches. The first-generation Monsters did have Seiko's in-house automatic movements but they were very limited in functionality. There was no hand-winding nor was there hacking seconds. The new generation Monsters use Seiko's 4R36 movement which does have hacking seconds and allows for hand-winding which is much preferable. These kinds of features are typically found in more expensive mechanical movements. Winding the SRP307 is very smooth and satisfying. The movement ticks at 21,600 bph.
The cool thing about this inexpensive automatic watch is that it's actually DIVER -rated to 200 meters. This is much better than simply being "water resistant to 200 m" and means the watch has gone through specific standardized tests to ensure it's water resistance for diving. The SRP307 has a screw-down crown to better ensure water resistance.
The lume on this watch is spectacular! Here's another look at the photo from above:
The watch features a unidirectional bezel and a DAY and DATE complication (in two languages). The stainless steel case and bracelet are high quality. The bracelet has a diver's extension. Personally I don't dive but I have found this useful during summer months to deal with wrist expansion.
I think it's safe to say that the design of the Monster has always been controversial with people either loving it or hating it. I like the bold and unique design of the Monster. It's a very heavy watch, which I don't mind, but what does somewhat bother me is it's massive size, measuring almost 43 mm in diameter. If you're into the big watch trend then this size is for you. It's just personally I prefer more classical sizes of 34 to 38 mm.
The clasp is double-deployant with a safety:
There's a reason the Seiko Monster, especially the newer generation with the 4R36 movement, has a cult following. They are a very inexpensive way to get a diver-rated watch with an in-house mechanical movement. I've come to refer to the Seiko SRP307 as "the poor man's Rolex Submariner" and it may just be the best bang-per-buck automatic diver's watch out there... but what do you think?