Some AS3340 prices in the US:
Synthcube $5.99 plus $8.39(!!!) shipping to my address (northeastern US).
ModularAddict $7.70 plus $4.15 shipping. Out of stock ATM.
AI Synthesis $7.00 plus $4 shipping.
(I recently bought three from them — and they actually sent three AS3340A chips. This is the impoved version which SynthCube sells for $8.99! However, the AI Synthesis page says AS3340, not AS3340A, and for all I know you might get either. You could ask.)
cabin-globa on eBay $7.20 plus $3.06 shipping.
Cabintech Global $6.33 plus $1.16 shipping! (Untracked, $3.06 tracked.)
Last two apparently the same seller, I haven’t bought from them but they have 99.7% feedback on eBay and their website’s been up since at least 2014.
Added: I see they were mentioned here… closing in on two years ago!
Added: I recently bought one AS3340 from Cabintech Global… No complaints.