AR ES 1 our buy a newer TY

Should I buy an AR ES 1 for 700.00 USD or look into a newer turntable.  I have a Marantz Model 18 with Dynaco A25’s recapped.  

Thanks so so much for all your advise. 
Depends on how much you want to spend, IMO. The price you've stated for the ES-1 (unless it comes with an arm) is higher than the selling price when it was new. I bought mine in the late 1980s for $500. Over the years I fully tricked out my ES-1 with just about every mod available from Merrill and Scillia. The mods did raise the performance of the table.
At that price you should get something new. There are plenty to choose from!
Too high a price for a stock ES-1!
I just checked EBay. Found 3 for sale. Prices range from $1K to $1.25K to (get this!) $6.8K!!! And the $1K was a "beater" in poor condition! The $6.8K one did have a Magnepan Unitrac arm, plus 4 cartridges (Shure V15 MR, two Pickering's and an AT 404). Apparently these are some VERY optimistic sellers!
I'd rather spend cash on a vintage Technics 1200 - and I did! A much better, right-out-of-the-box TT! Too much tweaking required for the ES-1!
Really appreciate everyone’s input.  I’m going to pass on it but, will keep looking.  I know the right one will come along. 
Want something new with warranty? For that $700 you could get a brand-new Pioneer PLX1000. Best TT under $1K! I have one in my collection! Made in Ch*na - but so what! So is my android phone! The PLX1000 is a quality piece that sounds excellent (see Herb Reichert's review in Stereophile). And is a lot more affordable than the newest Technics 1200 ($1.8K).
I had an AR ES-1 when it was first introduced, and liked it okay. But for $700 you can get what I consider to be a better table (with an arm of your choice, perhaps a Jelco), the one I replaced my ES-1 with: VPI HW-19 Mk.2 or Mk..3., commonly available (without arm) for around $500.