Finding a chip that can record and playback 30 seconds of audio
Sourcing from ebay's Chinese sellers is as simple as ordering and then waiting a few weeks until it arrives, so here's some from what eBay sellers offer:


ISD1820 DIP-14 8-20 seconds has a sampling rate of up to 8kHz (manufacturer writes that that supports up to 3.4kHz of audio frequency - enough for voice, but shabby for good audio) 2.7 - 4.5V supply voltage needed.
APR9301 SOP-28 20-30 seconds seems to also be meant for voice with it's 8kHz sampling rate, however for both devices nothing is said about trying to achieve higher frequencies. 4.5 - 6.5V supply voltage needed.
ISD1620BSY SOIC-16 13.3 seconds at 12kHz (better, but still rather muffled high ends to be expected) 2.4 - 5.5V supply voltage needed.
Various others 


If you're from the USA, you can look at something like this SparkFun product
if shipping time is a concern.

It's a matter of googling for voice recorder IC and checking if your favourite retailer stocks it.

Perhaps it would be best to buy a memory chip (for example M24128-DFCS6TP/K and a microcontrollers from your preffered company with an adequate clock frequency and do the recording that way. After the sound's been recorded, play it back by using a dedicated DAC (for example MCP4706A0T-E/CH) or using the microcontrollers peripherals.

Also, I can recommend AliExpress as an alternative to eBay, since sometimes things are offered cheaper there, but generally the prices are the same.

If you want to make a board to manufacture and sell later on, you should look at Farnell, Elfa and other large and reputable distributors for your electronics parts, since depending on the legitimacy of China sourced parts can sometimes be questionable (usually works fine for home use and one-off tinkering though).