You've hit me where I live. I love the selection available new and used in the $250.00 price range. It's my sweet spot. I have a couple customs that are more expensive, but I rarely carry because I'm afraid of screwing them up. I also have a few Cold Steel Voyagers and stuff like that that I don't carry much anymore because they're not cool enough and don't have the really top end blade steels that I like these days.
In the price range you're looking at it's obvious that you want more than just bang for the buck the joy a FRN handled $35.00 Spyderco delivers, as good of as that knife might be. You want a cool, well built and durable knife. The above mentioned used Sebenza would be a great place to start. But there's more to life than Sebenzas (although I do own and love a Sebbie).
You mention the Microtech Amphibian. I have one and it is one of my absolute favorite knives. The fit and finish is superb. The 154CM recurve blade holds a great edge and just loves to cut. The Microbar lock is solid and secure. It's big enough that it will occasionally freak people out but is not over-the-top big like a Benchmade 630. The ergonomics are perfect for me.
I also love my Microtech Socome Elite plain edge. These turn up sometimes in your price range and are awesome knives. I think the Amphibian is probably a better task knife and all around worker, but the Socom E is a bad arse tactical folder that's tough and refined at the same time. I like mine so much I had to get a spare
Been thinking about doing that with the Amphibian as well.
Pretty much anything made by Benchmade that says 941 on it should do you well if you want something cool, tough and a bit sleeker than the Microtechs mentioned above. The Ti/S30V limited edition is especially sweet and while it's list price was $220.00 when they were readily available, they do show up occasionally, but usually for a bit more than original list for a NIB one. I'd pay a bit more than original list and still feel like I got a good deal. The 941 Ti/S30V is an awesome knife! The Carbon Fiber/D2 model is nothing to sneeze at either, but those seem more rare. I guess everyone who has one likes it enough to keep it (me too). Even a basic 941 is a great knife, but the LE models are really top shelf.
The above mentioned Buck 172 Mayo is a great knife and often comes up for sale in the used section way under your price point. It's smaller than the Microtechs and sleek like the Benchmades. It has S30V (treated by the magical Paul Bos) and Ti handle/frame lock and was designed by Tom Mayo! Cool and tough only begins to describe this knife. I love mine and have a real Mayo to compare it to. The custom Mayo is nicer, but worth so much I rarely carry it, whereas the Buck version gets a lot of pocket time.
A Benchmade 750 Pinnacle would be a great alternative. It's a solid ATS34/Ti frame lock (sort of like Sebenza) that can be had for half what you've quoted. It's a really functional and tough knife that is cheap enough and plain enough that it invites you to "Pimp My Knife". If you have any propensity for customizing or thinking about making your own, the 750 is a great place to start. While the knife is very similar to a Sebenza on paper, the CRK is built to a higher standard of precision, but the Benchmade is still pretty good.
The last recommendation is my most recent aquisition. I've always looked at a Camillus EDC as a nice knife, but the steel frame and 154CM blade were not special enough to make me buy one. I almost bit with the AG Russel D2 version but still never could pull the trigger. I recently aquired a Camillus EDC with the Talonite blade and am blown away! It's small and sleek and a frame lock like the small Sebenza, but has totally different ergos and a steel frame as opposed to the Sebbie's Ti . The skelotinizing (sp?) and thin frame make it much lighter that I would have guessed and the Talonite recurve blade just LOVES to cut! These are discontinued and don't come up often but are an awesome choice for a smaller but still very tough EDC. I'm sure DDR's custom EDCs are worth the money having used this collaboration, but are well beyond the scope of this search. I can think of a couple friends that will get plain 154CM EDCs for Christmas this coming year.
Al Mar makes some solid knives in this price range that get great reviews. I own a Shrike and a SERE 2000. Both are tough, sharp and lock up well, but rarely find themselves in my pocket. They're more like the Microtechs in size and weight, but don't light my fire. I'll never sell the SERE 2000 as it belonged to a now gone friend, but the Shrike will probably be gone soon (email me if you're interested).
An EDC is a very personal choice, but the above mentioned knives all see a regular position in my pocket and are highly recommended.
Good luck in your search.
John
