Try Ebay. There are always Walbro carbs for sale there for anywhere from $5 to $25. I've even seen a whole dozen of brand new take-offs go for less than $50. I just bought a WT-324 (11.1mm venturi) for $17. Probably not the best deal I could've gotten, but heck, I need one for a 33cc I'm playing with. The same guy still has several other similar ones for sale.