Something else I can't believe I forgot to mention...
Synthmaster, since it does multiple forms of synthesis, has the ability to add soundfonts and wave tables and you can pick up the basic synth for around $70.00.
But then again, you still haven't really told us anything in real detail of 'this synth' except it has to have the sound, the options and the capabilities. Pretty vague.
But definitely download the Synthmaster demo since you could buy it well within your budget.
