Things like invisibility & going incorporeal help with escaping.
I'll go ahead and post what magic items I know of even though it might be out of your price range (not sure what the characters can afford):
Ability, Aporter Armor or Shield - MIC pg 6 (2x/day teleport 800-ft as Dimension Door spell)
Ability, Dislocator Weapon - MIC pg 32 (3x/day when hit, teleport enemy 10-ft as you choose, may help you in your retreat)
Ability, Vanishing Weapon - MIC pg 45 (1x/day if hits, teleport self up to 60-ft as Dimension Door spell)
Runestaff of Passage - MIC pg 181 (3x/day cast Astral Projection, Dimension Door, Great Teleport, Passwall, & Phase Door spells if expending arcane spells of same lvl or higher)
Runestaff of Transportation - MIC pg 182 (3x/day cast Blink, Dimension Door, & Teleport spells if expending arcane spells of same lvl or higher)
Belt, of the Wide Earth - MIC pg 204 (2x/day lose spell of 5th-9th lvl to cast Teleport spell)
Boots, of Big Stepping - MIC pg 76 (3x/day teleport 60-ft as Greater Teleport spell)
Boots, Dimension Stride - MIC pg 94 (3 charges to Teleport, 1 = 20-ft, 2 = 40-ft, 3 = 60-ft)
Boots, of Swift Passage - MIC pg 78 (5x/day teleport up to 20-ft as move action)
Boots, of Teleportation - DMG pg 250 (3x/day cast Teleport spell)
Helmet, of Teleportation - DMG pg 259 (3x/day cast Teleport spell)
Bolt Shirt - MIC pg 75 (1x/day Teleport self 60ft in line of sight)
Ability, Quickness Armor - MIC pg 13 (+5-ft land speed)
Ability, Speed Armor or Shield - MIC pg 14 (3x/day gaint Haste spell for 1 rnd, will gain +30 speed)
Acrobat Boots - MIC pg 67 (3 charges, 1 = +10 speed, 2 = +15 speed, 3 = +20 speed for 1 rnd)
Boots, of Desperation - MIC pg 77 (3x/day +30 speed)
Quicksilver Boots - MIC pg 119 (2x/day swift full speed)
Boots, of Speed - DMG pg 250 (Cast Haste spell for 10 rnds/day, will gain +30 speed)
Boots, of Striding & Springing - DMG pg 250 (+10 speed)
Chronocharm, of the Horizon Walker - MIC pg 86 (1x/day move up to extra half speed as swift action)
Cloak, Phoenix - MIC pg 210 (Gain fly speed = to land speed)
Cloak, Wings of Flying - DMG pg 268 (Turns into pair of bat or bird wings with 60-ft fly speed)
Mask, Panther - MIC pg 201 (gain a +5 to speed)
Sandals, of the Light Step - MIC pg 198 (+10-ft enhancement speed bonus)
Sandals, of Sprinting - MIC pg 131 (3x/day gain +30ft speed for 1 rnd)
Slippers, of Battledancing - DMG 2 pg 272 (+10 speed)
Vest, Winged - MIC pg 195 (5x/day can fly with manticore wings)
War Wizard Cloak - MIC pg 147 (1x/day cast Dimension Door)
Ring, Invisibility - DMG pg 232 (Turn invisible as the Invisibility spell)
Ring, of Vanishing - MIC pg 128 (Turn invisible as the Greater Invisibility spell)
Vanisher Cloak - MIC pg 145 (3 charges, 1 = become invisible 4 rnds, 2 = you & adjacent ally become invisible 3 rnds, 3 = you & 3 adjacent allies become invisible 2 rnds)
Cloak, of Shadow - PLHB pg 82 (turn incorporeal 1x/day 1 min)