My first thought is to throw a little extra down for one of the Volcas. I though I saw them for about $120 on Amazon last week; but their current price of $160 is really stretching the budget. The Monotron Delay looks good for making really weird sci-fi type sounds: http://www.amazon.com/Korg-Monotron-Analog-Ribbon-Synthesizer/dp/B00684KFAM/