I haven't used it myself but I've head some good things about Mackie's Traktion. Which is basically a sequencer in the cubase sense (rather than a tracker) but only costs about $150
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Myself I use Cubase SL 2, of which i bought second hand for about 150 Euro, so that's not too bad either. I use this in conjunction with a Creamware Scope system, some VSTi's (Battery, Albino 2, ImpOscar) and a Nord Rack II.