Here's when various HP terminals were introduced,
and when they were discontinued, along with their prices:

...sorted by date (and model number within date):

   Model | 1979     1980    1981    1982     1983  1984    1985  Notes
   ------|-----------------------------------------------------  --------------------
   2640B | $2600   $2600       x       x        x      x      x  (introduced 1976)
   2640C | $4250   $4250       x       x        x      x      x  Cyrillic
   2641A | $4100   $4100       x       x        x      x      x  APL
   2645A | $3500   $3500   $3500   $3995    $4550  $4600      x
   2645K | $4000   $4000       x       x        x      x      x  Katakana
   2645N | $3750   $3750       x       x        x      x      x  Danish/Norwegian
   2645R | $4350   $4350       x       x        x      x      x  Arabic
   2645S | $3750   $3750       x       x        x      x      x  Swedish/Finnish
   2647A | $8300   $8300       x       x        x      x      x  b&w graphics, BASIC
   2648A | $5500   $5500   $5950   $6530        x      x      x  b&w graphics
   2649A | $2150   $2150   $2150       x        x      x      x
  13290B | $6950   $6950   $6950       x        x      x      x  2648A + more
   2621A |         $1450   $1595       x        x      x      x
   2621P |         $2550   $2650   $2750        x      x      x  integral thermal printer
   2675A |         $3400      xx       x        x      x      x  No CRT, "Therminal", modem
   2626A |             -   $3950   $4150    $4350  $4400  $4900
   2642A |             -      ??   $6750        x      x      x
   2647F |             -   $8950   $9400    $9950  $9950      x  b&w graphics, BASIC
   2649I |             -   $7750       x        x      x      x  2649A - graphics
   2382A |             -       -   $1700    $1700  $1720      x  codename "shadow"
   2622A |             -       -   $2075    $2175  $2210      x
   2623A |             -       -   $3750    $3750  $3250  $3250  b&w graphics
   2624B |             -       -   $2890    $3000  $3035  $3035
   2703A |             -       -  $24000       ??     ??      x  "2700"
   2621B |             -       -       -    $1595  $1295      x
   2627A |             -       -       -        -  $5975  $5975  color graphics
   2392A |             -       -       -        -      -  $1295
   2625A |             -       -       -        -      -  $3495  dual, opt graphics
   2628A |             -       -       -        -      -  $3195  HPWORD

	 
... sorted by model number:


   Model |  1980    1981    1982     1983  1984    1985  Notes
   ------|---------------------------------------------  --------------------
   2382A |             -       -   $1700    $1700  $1720      x  codename "shadow"
   2392A |             -       -       -        -      -  $1295
   2621A | $1450   $1450   $1595       x        x      x      x
   2621B |             -       -       -    $1595  $1295      x
   2621P | $2550   $2550   $2650   $2750        x      x      x  integral thermal printer
   2622A |             -       -   $2075    $2175  $2210      x
   2623A |             -       -   $3750    $3750  $3250  $3250  b&w graphics
   2624B |             -       -   $2890    $3000  $3035  $3035
   2625A |             -       -       -        -      -  $3495  dual, opt graphics
   2626A |             -   $3950   $4150    $4350  $4400  $4900
   2627A |             -       -       -        -  $5975  $5975  color graphics
   2628A |             -       -       -        -      -  $3195  HPWORD
   2640B | $2600   $2600       x       x        x      x      x  (introduced 1976)
   2640C | $4250   $4250       x       x        x      x      x  Cyrillic
   2641A | $4100   $4100       x       x        x      x      x  APL
   2642A |             -      ??   $6750        x      x      x
   2645A | $3500   $3500   $3500   $3995    $4550  $4600      x
   2645K | $4000   $4000       x       x        x      x      x  Katakana
   2645N | $3750   $3750       x       x        x      x      x  Danish/Norwegian
   2645R | $4350   $4350       x       x        x      x      x  Arabic
   2645S | $3750   $3750       x       x        x      x      x  Swedish/Finnish
   2647A | $8300   $8300       x       x        x      x      x  b&w graphics, BASIC
   2647F |             -   $8950   $9400    $9950  $9950      x  b&w graphics, BASIC
   2648A | $5500   $5500   $5950   $6530        x      x      x  b&w graphics
   2649A | $2150   $2150   $2150       x        x      x      x
   2649I |             -   $7750       x        x      x      x  2649A - graphics
   2675A |         $3400      xx       x        x      x      x  No CRT, "Therminal", modem
   2703A |             -       -  $24000       ??     ??      x  "2700"
  13290B | $6950   $6950   $6950       x        x      x      x  2648A + more

And, some terminals not in the above tables (thanks to hpmuseum.net):

   2752A Teleprinter (1966)
   2600A (1972; $4250; rebadged Datapoint 3300)
   2615A (1974; $2750; rebadged MiniBee (Beehive Medical Electronics Company))
   2640A (1974; $3500))
   9882A (1975; $4675; 2640A + interface card to talk to HP 9830A))
   307X Data Capture Terminals (1976)
   3081A Data Collection Terminal (1983)
   3092A Industrial Terminal (1983; $4305; industrial; 2622A compatible)
   2393A Monochrome Terminal (1985; $2095))
   2397A (1985; $3095; color)
   9666A Rugged Terminal (1986)
   3082A Touch Terminal (1987)
   700/92 (1987)
   700/X Terminal (1989)
   700/RX (1991)

Note: the 2642A is in the 1981 catalog, but without a price.

Most model/price information above is based on entries in the yearly "HP Test &
Measurement Catalog".  Thus, the granularity is a single year.  (Prices don't 
include cartridge tape ($1600 extra)/ floppy drives, where available.)
(I didn't check for discontinuance of any terminal past 1985.)

In 1985, HP suddenly realized how important computers were,
so they were moved to the front of the T&M catalog!

HP 2675A (Therminal) information from http://hpmuseum.net/display_item.php?hw=711
GP 2703A (2700) information from http://hpmuseum.net/display_item.php?hw=244

Personal Computer Notes:

   HP 125, HP 120       Introduced in 1984.   gone by 1985
   HP 150, HP 110       Introduced in 1985.   gone by 1988

HP 300 note:

   gone by 1983

Updated: 2000-08-29, 2017-05-24