I believe a portable Amp is a must have for Ventriloquists. You'll be able to use it either in situation where you do not have access to electricity or if you do. I find that the louder I try to speak the more likely I might move my lips. If I had a PA system 25 years ago, I would have been venting back then.
You can not go wrong with the Hisonic Portable Amp, that Ax sells.
Also a lot of entertainers like the Happie Amp.
I now own 2 truly rechargeable portable Amps, and 2 that use to be rechargeable, but no longer hold a charge, but yet I still use them when I have access to electricity.
I also own a larger system, for the times when I'm doing a show in a larger environment, but this system requires electricity.
You'll find many vents and magicians swearing by different brands.