Hello C-B!!!
Lord--what a question!!! Being fearless, I will tread where others
hesitate, and give you some hard numbers:

Under $500--parts car.
$500 to $1,000--runs, but needs damn near everything.
$1,000 to $2,000--sound operation; may look careworn OR rather sexy.
$2,000 to $3,000--Better be pristine condition, with the receipts
to prove it, AND should have an R-Sport instrument
cluster (IF you buy it and live with it awhile,
you'll learn what this means; by then, you'll
be ONE OF US!!! ONE OF US!!! ONE OF US!!!
That's from a light-hearted Tod Browning film.)

But remember--we are discussing a 30-YEAR-OLD mechanical device
here. The price is not the real issue. Are you buying from a friend
or stranger??? Are you mechanically inclined--a tinkerer--a wrenchhead???
Does it bother you if graying Yuppie neighbors with SUV'S mutter about"that
tacky Swedish heap in his driveway"??? Buy an SUV instead--then you
can be ONE OF THEM!!! ONE OF THEM!!! ONE OF THEM!!!
Is this to be your primary transportation, or a hobby/fun/restoration
fling??? If it's to be your primary ride--DON'T BUY IT!!! Do you
have any grasp of what that 'E' on the model number means??? It stands
for an antique system of German 'Einspritzen' fuel-injection termed 'D-Jetronic".
Even if you can afford to hire-out service chores, you'll find it
near impossible to locate a shop/technician who is competent with
this layout. All the experts are dead or in Rehab. You'll have to put in
the time/study/frustration to become an expert on it YOURSELF!!!
For comparison, imagine finding a tech/and/or parts to tend a 1985
Atari computer.
By now, you're asking, "What gives HIM the gall to take-up so much
of Cyber-Space with his jejune rantings??? Well . . . for one thing,
I bought a new 1.75 of Tanqueray today (The Brits may have wanked-away
their Empire, but they can still excrete that Life-Sustaining Gin.)
On the other hand (HA-HA), I've lived with three 164's over the last
25 years. WHY did I tolerate these museums-on-wheels??? Well, after
you gain a certain body-of-knowledge, there IS satisfaction in
knowing that you could perform a roadside repair on almost any area
of the thing--that's one advantage of 'antique' technology. And--
you don't see one of them driving toward you every two minutes in
the opposing lane.
Finally, even though I'm an OLD guy, I do enjoy the exchange/banter/
levity we share here, but I must . . . wait, where's my CIGAR . . .
WINONA STOLE IT!!! . . .but I must say . . . 122's are for arthritic
Hippies still listening to Jethro Tull 8-Tracks--with Birkenstocks.
Can the Old Cigar-Chomper still stir it up, or what???

Gary in Arizona