The Collaborative International Dictionary of English v.0.48:

Extravagantly \Ex*trav"a*gant*ly\, adv.
   In an extravagant manner; wildly; excessively; profusely.
   [1913 Webster]

WordNet (r) 3.0 (2006):

extravagantly
    adv 1: in an abundant manner; "they were abundantly supplied
           with food"; "he thanked her profusely" [syn:
           abundantly, copiously, profusely, extravagantly]
    2: in a wasteful manner; "the United States, up to the 1920s,
       used fuel lavishly, mainly because it was so cheap" [syn:
       extravagantly, lavishly]
    3: in a rich and lavish manner; "lavishly decorated" [syn:
       lavishly, richly, extravagantly]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "extravagantly":
   abominably, abundantly, affluently, agonizingly, aplenty, awfully,
   baldly, balefully, beyond measure, bitterly, blatantly,
   bottomlessly, bounteously, bountifully, brashly, confoundedly,
   copiously, cruelly, damnably, deadly, deathly, deucedly, diffusely,
   distressingly, dolorously, dreadfully, effusely, egregiously,
   elaborately, elegantly, excessively, excruciatingly, exorbitantly,
   extortionately, exuberantly, flagrantly, frightfully, fully,
   generously, gloriously, gougingly, grandiosely, grandly,
   grievously, grossly, hellishly, horribly, immoderately, imposingly,
   impressively, improperly, in abundance, in full measure,
   in good supply, in plenty, in quantity, inexcusably, inexhaustibly,
   infernally, inordinately, intolerably, lamentably, lavishly,
   liberally, luxuriously, magnificently, majestically, maximally,
   miserably, more than enough, nakedly, no end, nobly, openly,
   opulently, out of measure, outrageously, overabundantly,
   overflowingly, painfully, piteously, plenteously, plentifully,
   preposterously, prodigally, profusely, proudly, richly, riotously,
   sadly, shatteringly, shockingly, something awful, something fierce,
   sorely, splendaciously, splendidly, splendiferously, staggeringly,
   sumptuously, superabundantly, superbly, terribly, to the full,
   torturously, unashamedly, unbearably, unconscionably, unduly,
   unpardonably, unreasonably, usuriously, without measure,
   woefully