I don't know if such a build already exists, sorry if it does.

I wanted to create a haggletoon with the least effort and max haggle.
I don't know if its the best possible class mix but i couldn't find a better one.
For this you will need access to create a Purple Dragon Knight.

Code:
Character Plan by DDO Character Planner Version 04.19.02
DDO Character Planner Home Page

Level 15 True Neutral Purple Dragon Knight Male
(1 Fighter \ 13 Rogue \ 1 Sorcerer) 
Hit Points: 188
Spell Points: 230 
BAB: 10\10\15\20
Fortitude: 8
Reflex: 10
Will: 6

                  Starting          Feat/Enhancement
Abilities        Base Stats          Modified Stats
(32 Point)       (Level 1)             (Level 15)
Strength              8                     8
Dexterity            15                    15
Constitution         14                    14
Intelligence         10                    10
Wisdom                8                     8
Charisma             18                    22


Level 1 (Fighter)
Feat: (Fighter Bonus) Dodge
Feat: (Selected) Negotiator
Feat: (Human Bonus) Skill Focus: Haggle


Level 2 (Sorcerer)


Level 3 (Rogue)
Feat: (Selected) -


Level 4 (Rogue)


Level 5 (Rogue)


Level 6 (Rogue)
Feat: (Selected) -


Level 7 (Rogue)


Level 8 (Rogue)


Level 9 (Rogue)
Feat: (Selected) -


Level 10 (Rogue)


Level 11 (Rogue)


Level 12 (Rogue)
Feat: (Selected) -
Feat: (Rogue Bonus) Skill Mastery


Level 13 (Rogue)


Level 14 (Rogue)


Level 15 (Rogue)
Feat: (Rogue Bonus) Skill Mastery
Feat: (Selected) -
Enhancement: Purple Dragon Knight - Human Versatility: Skill Boost (Rank 1)
Enhancement: Purple Dragon Knight - Human Adaptability: Charisma (Rank 1)
Enhancement: Purple Dragon Knight - Cormyrean Knight Training (Rank 1)
Enhancement: Purple Dragon Knight - Action Surge: Charisma (Rank 1)
Enhancement: Purple Dragon Knight - Action Surge: Charisma (Rank 2)
Enhancement: Purple Dragon Knight - Action Surge: Charisma (Rank 3)
Enhancement: Purple Dragon Knight - Improved Recovery (Rank 1)
Enhancement: Purple Dragon Knight - Ambidexterity (Rank 1)
Enhancement: Purple Dragon Knight - Improved Recovery (Rank 1)
Enhancement: Purple Dragon Knight - Heroism (Rank 1)
Enhancement: Purple Dragon Knight - Greater Heroism (Rank 1)
Enhancement: Stalwart Defender (Ftr) - Toughness (Rank 1)
Enhancement: Stalwart Defender (Ftr) - Threatening Countenance (Rank 1)
Enhancement: Stalwart Defender (Ftr) - Threatening Countenance (Rank 2)
Enhancement: Stalwart Defender (Ftr) - Threatening Countenance (Rank 3)
Enhancement: Fire Savant (Sor) - Fire Savant (Rank 1)
Enhancement: Fire Savant (Sor) - Intensity (Rank 1)
Enhancement: Fire Savant (Sor) - Intensity (Rank 2)
Enhancement: Fire Savant (Sor) - Intensity (Rank 3)
Enhancement: Thief-Acrobat (Rog) - Staff-Control (Rank 1)
Enhancement: Thief-Acrobat (Rog) - Charming (Rank 1)
Enhancement: Thief-Acrobat (Rog) - Charming (Rank 2)
Enhancement: Thief-Acrobat (Rog) - Charming (Rank 3)
Base Haggle 17,5
Char-Mod* +6
*with Purple Dragon Knight - Human Adaptability: Charisma (Rank 1)

23,5

Feats:
Negotiator(feat) +2
Skill Focus(Haggle) +3
Skill Mastery(2 times) +2

30,5

Enhancements:
Negotiator(pdk tree) +3
Threatening Countenance +3
Intensity(Sor) +6
Charming(Rog) +3

45,5

Buffs:
PDK Greater-Heroism +4
Skill Boost+Cha Surge +5

54,5

Misc:
PDK Gear (cha +6 item ) +3
+1 Skill Tome +1

58,5 only with the Stock Build

Special:
MotU Mask +1
+15 HaggleItem +15
Airship Cha +2 +1

75,5

If you are lucky and have a +15 Haggle item for lvl 15 you easily can reach 75,5 Haggle without effort.