Nib grade
The middle grade, and the one most pens shipped with. A medium lays down enough ink to show off its color and still fits ruled paper. It's also the most forgiving grade to buy secondhand, since small wear on the tip shows less than on a fine. Look at the tip in the photos anyway. A flat spot worn at an angle means the pen was used at a steep slant, and it may feel scratchy until a nib worker smooths it.
34 pens we cover.

Parker · 1941–1948
VacumaticVacumatic filler, 1941 to 1948
Pre-war and wartime
$100–$210 typical ask
35 on eBay

Parker · 1948–1969
AerometricAero-metric filler, 1948 to 1969
Post-war golden age
$130–$270 typical ask
31 on eBay

Parker · 1937–1948
VacumaticMid-size Vacumatic, 1937 to 1948
Pre-war and wartime
$140–$240 typical ask
25 on eBay

Parker · 1921–1936
Button and lever fillerPermanite flat-top, late 1920s
Pre-war and wartime
$270–$490 typical ask
26 on eBay

Parker · 1964–1994
Cartridge and converterSterling silver crosshatch, 1964 to 1994
Post-war golden age
$140–$210 typical ask
37 on eBay

Parker · 1964–2007
Cartridge and converterBrushed stainless steel, from 1964
Post-war golden age
$55–$90 typical ask
30 on eBay

Parker · 1937–1948
VacumaticLadies' size Vacumatic, 1937 to 1948
Pre-war and wartime
$200–$290 typical ask
12 on eBay

Parker · 1948–1965
AerometricMark I, 1948 to 1951
Post-war golden age
$25–$40 typical ask
34 on eBay

Parker · 1948–1960
AerometricShorter 51, 1948 to 1960
Post-war golden age
$100–$190 typical ask
10 on eBay

Montblanc · 1952–present
PistonPrecious resin, 1980s
Modern
$525–$775 typical ask
29 on eBay

Montblanc · c. 1950–early 1960s
PistonCelluloid, 1950s
Post-war golden age
$1,275–$1,625 typical ask
5 on eBay

Montblanc · 1950s
PistonCelluloid, 1950s
Post-war golden age
$725–$1,050 typical ask
11 on eBay

Montblanc · c. 1968–1978
PistonPiston-filling 22x series, 1970s
Modern
$130–$230 typical ask
25 on eBay

Montblanc · 1950s–1960s
PistonGold-nib student pen, 1950s
Post-war golden age
$190–$290 typical ask
24 on eBay

Montblanc · 1980s–early 2000s
Cartridge and converterSlim cartridge pen
Modern
$270–$380 typical ask
39 on eBay

Sheaffer · 1952–1959
Snorkel and TouchdownPalladium silver Triumph point, plastic cap
Post-war golden age
$75–$170 typical ask
10 on eBay

Sheaffer · 1952–1959
Snorkel and TouchdownGold-filled cap, 14K two-tone Triumph point
Post-war golden age
$180–$250 typical ask
4 on eBay

Sheaffer · 1959–1968
Snorkel and TouchdownPlastic cap, gold-filled band, 14K inlaid nib
Post-war golden age
$260–$320 typical ask
6 on eBay

Sheaffer · 1929–1942
Button and lever fillerStriated Marine Green, lever filler, 1937
Pre-war and wartime
$110–$190 typical ask
36 on eBay

Sheaffer · 1976–1998
Cartridge and converterMatte black, gold-plated trim, Classic size
Modern
$110–$200 typical ask
11 on eBay

Sheaffer · 1949
Snorkel and Touchdown1949 only, Touchdown filler
Post-war golden age
$85–$210 typical ask
15 on eBay

Pilot · 1992–present
Cartridge and converter14K size 5 nib, cartridge or converter
Modern
$140–$210 typical ask
26 on eBay

Pilot · 2000–present
Plunger (vacuum)Plunger filler, 14K size 15 nib
Modern
$480–$600 typical ask
27 on eBay

Pilot · 1963–present
Cartridge and converterClick-action Capless, from 1964
Post-war golden age
$150–$230 typical ask
35 on eBay

Pilot · 1971–1980
Cartridge and converterModel M-350SS, integral steel nib
Modern
$230–$360 typical ask
28 on eBay

Pilot · 1964–1973
Cartridge and converterFirst-generation pocket pen, 14K nib
Post-war golden age
$110–$180 typical ask
28 on eBay

Pilot
Cartridge and converterModern
$30–$55 typical ask
12 on eBay

Pelikan · 1982–present
PistonGreen striped, old-style trim, 1982 to 1997
Modern
$290–$380 typical ask
27 on eBay

Pelikan · 1987–present
PistonBlack, old-style trim, before 1997
Modern
$500–$750 typical ask
17 on eBay

Pelikan · 1985–present
PistonSteel nib, old-style trim, 1985 to 1997
Modern
$140–$250 typical ask
27 on eBay

Pelikan · 1956–1965
PistonThird version of the 400, 1956 to 1965
Post-war golden age
$260–$340 typical ask
24 on eBay

Pelikan · 1929–1944
PistonThe first Pelikan, celluloid barrel
Pre-war and wartime
$400–$550 typical ask
10 on eBay

Pelikan · 1985–present
PistonOld-style, M400-sized, 1985 to 1997
Modern
$350–$525 typical ask
16 on eBay

Pelikan · 1997–present
PistonBlack, two-chick logo, 1997 to 2003
Modern
$900–$1,200 typical ask
26 on eBay