Reasonable moving coil cartridge

I don't even know why you guys are going on and on about re-tipping rebuilding. he's looking at a $300 cart who in their right mind re-tips a $300 cart more economical to buy a new one. Ok ok I know someone has a ultra rare cart they love and will pay to re tip it but 99% of the rest just toss it and buy new at those price levels. 

Ok rant done,

 I agree with the others stick to MM-MI in that price. 
The Denon as much as people gush over it its a dud IMO (conical tipped) Its fine if your looking for that 70's rock sound ie boomy bass, descent mids and rolled off highs but really its a budget MC when the higher end MM's in the same price range are better. Sticking a different body or tip on it helps but its never going to be a $600 cart even with $500 added on in upgrades. Ok my opinion after owning one and trying to get decent sound out of it. 

After owning a VDH MC 10 for 20 years I cannot recommend faster the VDH mc 10 as an entry level MC cart. you'd have to save up some though. The Van Den Hull MC10 its their entry level LOMC and its got 90% of the VDH upper end and of course VDH's fantastic Stylus profile. I think its a great value, you see them for around a grand new. Rebuildable of course and excellent  longevity. I've had mine rebuilt cost about 40% of the new cost. 

Glen 

Any LOMC about less than $800 or so is probably not going to be any better than a good MM or MI cartridge.

Go with MM or MI, with something like a Nagaoka MP300 or MP500 or Ortofon 2M black or Godring 2400 (or similar). You can get them almost half price on ebay. Only a few weeks ago, on ebay, I found an MP500 for less than $250 with a broken stylus and got an MP300 stylus for it.

Note that although these "esoteric" styli types (line contact, shibata etc), are highly touted, some are EXTREMELY finnicky to set up to get their angles correct. An elliptical or an hyper elliptical will be much less sensitive to this (and much cheaper). MP500 will accept either an 300 or a 500 styli. 2M black will also work perfectly well with a 2M blue stylus too.

At my teenage years of 62, I doubt I can hear the nuances any cartridge can offer which is more than about 300 bucks.

Hana EL or EH $475
LOMC or HOMC
https://www.audioadvisor.com/prodinfo.asp?number=HAE

second @merosen40 - owned them both and they are excellent entry level cartridges for the money. That was two years ago and as most of here know, I fell into the rabbit hole and started to upgrade my TT and cartridges. And I can tell you that from experience (now Linn Sonedek LP12 with Koetsu Black cartridge - bought used) that there is noticeable difference in all aspects of ugrading your sound experience, turntable included. The trick IMHO is to first make a slight upgrade change (as you are), spend some time enjoying your new sound, for more than a while...then and only then begin to upgrade components that match your system. AND listen to this group in its entirety, there are some really experience audiophile people who have been in your exact shoes...maybe the better question to ask the group is you are interested in purchasing a new TT with cartridge for $X dollars and like the idea of a removable head. I think you will get some great answers. Enjoy the ride !!

Look on Ebay for an AT-12sa vintage cartridge you can find NOS for around $200.00 - $300.00 I picked one up a couple of months ago for $155.00 and then bought a NOS original stylus for another $55.00Shibata stylus MMOr if you want to spend a little more you can look for a vintage NOS AT-15sa for around $250.00 then just buy a NOS stylus for around
another $150.00 - $200.00Best yet upgrade your TT to at least an MH 3.3 or 5.3 TT otherwise as stated above just wasting your money on a cartridge that is going on an economy TT