Have you tried contacting Honeywell or or one of the other manufacturers of TCAS systems?
Unfortunately, it's not as simple as pushing a button in the cockpit and recording them. You have to jump through flaming hoops to simulate the conditions which generate the messages. i.e. using a variety of test equipment (a somewhat lengthy process).
BTW, there's probably already a desktop simulator or two on the market which has this feature. Perhaps you should check with your local Flight Sim software shop?
Please note that there are 3 or more different voices available on the real aircraft. You could just as well record your own and none would be the wiser
Rgds.
Q.