comments on below script:

2.  choice based on stored variable to rotate (esp. for "pardon" phrases)
4.  hint in text

/synonym [weapon] [wares] axe axes spear spears mace maces weapon weapons dagger daggers
/synonym [wares] [sword] weapon blade blades weapons
/synonym [sword] sword swords
/synonym [negation] no not don't can't afraid nothing never
/synonym [affirmation] yes sure okay

-- responses to others addressing the vendor
/filter from 0 to 1 source * /hear ** [sword] ** Vendor **
    /focus source
    /filter from 1 to 10
    /ic Hello.  How can I help you today?
/filter from * to * source * priority -100 /hear ** Vendor **
    /ic One moment please, I'm helping this person here.

-- timeout after about one minute
/filter from 0 to 0 priority -99 /wait 2000
/filter from * to 90 priority -100 /wait 2000
    /ic Let me know if you need help.

-- state for use whenever returning to the base state
/filter from 90 to 0
    /focus cancel

-- introduced, time to sell something
/filter from 10 to 90 /hear ** [negation] **
    /ic Pardon?  You don't need help right now?  Just call if you need help, then.
  /filter priority -1 from 10 to 11 /hear ** [wares] **
    /ic Here's a nice sword.
    /filter from 11 to 12
    /ooc (shows sword)
    /filter from 12 to 30
    /ic Is that something you'd like?
  /filter priority -2 from 10 to 20 /hear **
    /ic I sell swords.  Can I help you with a sword, perhaps?

-- customer knows we only sell swords
/filter priority -1 from 20 to 90 /hear ** [negation] **
    /ic Very well, then.  Just call if you need help.
/filter priority -2 from 20 to 11 /hear ** [sword] **
    /ic Here's a nice sword.
/filter priority -10 from 20 to 20 /hear **
    /ic Pardon?  I only sell swords, I'm afraid.

-- showing the sword
/filter priority -10 from 30 to 40 /hear * [affirmation] **
    /ic It's yours for 20 silver.
  /filter priority -11 from 30 to 31 /hear ** [negation] * [sword] **
    /filter from 31 to 30
    /ic I'm sorry, all we have are swords.
  /filter priority -12 from 30 to * /hear ** [wares] **
    /ic I'm afraid that's all we have.
  /filter priority -13 from 30 to 31 /hear ** [weapon] **
  /filter priority -14 from 30 to 90 /hear * [negation] **
    /ic I'm afraid that's all we have.  I'm sorry I can't help you.
  /filter priority -15 from 30 to * /hear **
    /ic Pardon?

-- offered the price
/filter from 40 to 90 /hear ** [negation] **
    /ic I'm sorry I couldn't find something you wanted.  Perhaps next time.
  /filter priority -11 from 40 to 41 /hear * [affirmation] **
    /ooc (accepts money)
    /filter from 41 to 42
    /ic Thanks!  Here's the sword.
    /filter from 42 to 43
    /ooc (gives sword)
    /filter from 43 to 90
    /ic Have a nice day!
  /filter priority -100 from 40 to 40 /hear **
    /ic Pardon?  Would you like the sword for 20 silver?