Would a Technics SL-1200 MK2 be an upgrade from a Denon DP-31L?

yep buy local when you can test it and offer lower dollar.

Technics dust cover cost maximum $60 new, i have never used dust covers for my pair of SL1210mk2 since i’ve bought them in 1996. All parts for sl1200 available online everywhere.

$400 is a waste of money on Technics SL1200mk2, you can buy a much better used direct drive Denon, Victor or better Technics (such as SP10mk2) for a little more, but without tonearm.

Stock SL1200 tonearm is a weak point anyway, even with kab fluid damper and totally rewired. I don’t know what you expect from this Technics Sl1200mk2, your cartridge must be really good (mid or high compliance) to make this deck sing. Some other expensive mods simply not worth the price (better just buy SP10mk2).

However, If someone telling you that cheap modern plastic decks like Audio-Technica, Pioneer or other "clones" of Technics are good, i will tell you there is nothing like Technics Sl1200 in terms of build quality. I’ve been using them for 20 years. This is legendary turntable made like the real thing!

I prefer my Technics SP20 and SP10mk2

I have a 1200 mk2 and like it a lot. It is stock with an AT120 cartridge. I use the Technics overhang gauge and never have an issue with anything, it just plays records, no fiddling. 

Mine me was used but very clean. Personally, I would not buy a unit that had been abused or missing parts.

Well,I have got 2 cents worth. I've used and modded Technics 1200's. It does look like a DJ table, but dead stock, I prefer it over most entry level tables.  The audio Technica mentioned, needs the phono pre removed at a minimum and really could use a ton of damping before it will get in the league of a stock sl1200. However Audio Technica does have an SL1240. As long as you remove the phono preamp, it competes nicely.  Then lastly, in the last month or so, I have purchased 3 vintage fixer uppers, that were all 3 inexpensive and when I'm finished, each will be quite good.... a Technics SL25 with an Audio Technica ATP-12T arm, a Miida turntable that was made by Denon, it is a nice table with fully adjustable arm and a Sony PS-X60 which has a very nice adjustable on the fly tone arm.  I have no doubt that if you are patient, you'll come across a steal out there.  Not a real recommendation on which way to go, but here are some alternatives to think about. I hope this helps, Tim

The Sony psx 60 is the best, imo. 

Comparing the new 1200 to the old is not close. 

It is like comparing an old, watered down 4 cylinder, low horse powered Mustang to a new high horse power muscle car Mustang of today. Well, maybe not that bad.....but I think you get my drift.

I agree that an sp 10 or 15 is a better choice. Yes, you'll need to get an arm for them but the arm on on the 1200 is compromised and for best performance will need to be replaced. Meaning your better off just doing it right in the first place.

I personally wouldn't buy a 1200, however, if I got him down to 150 to 200 I would play with it, mod it and have fun with it.