tidy sum
     n : often followed by `of' a large number or amount or extent;
         "a batch of letters"; "a deal of trouble"; "a lot of
         money"; "he made a mint on the stock market"; "it must
         have cost plenty" syn: batch, deal, flock, good
         deal, great deal, hatful, heap, lot, mass, mess,
          mickle, mint, muckle, peck, pile, plenty, pot,
          quite a little, raft, sight, slew, spate, stack,
          wad, whole lot, whole slew
see also:
batch deal flock good deal great deal hatful 
heap lot mass mess mickle 
mint muckle peck pile plenty 
pot quite a little raft sight slew 
spate stack wad whole lot whole slew 

76 moby thesaurus words for "tidy sum":
   a mass of, a world of, army, batch, bevy, bunch, cloud, clutter,
   considerable, covey, deal, flight, flock, flocks, gobs, good deal,
   good sum, great deal, hail, heap, heaps, heaps of gold, hive, host,
   jam, large amount, large sum, lashings, legion, loads, lot, lots,
   many, masses of, mess, millions, mint, mint of money, mob,
   muchness, multitude, nest, numbers, oodles, pack, peck, pile,
   piles, plurality, pot, potful, power of money, pretty penny,
   quantities, quite a few, quite a little, raft, rafts, rout, ruck,
   scads, scores, shoal, sight, slew, slews, spate, stack, stacks,
   swarm, thousands, throng, wad, wads, whole slew, worlds of