The best amplifier (and usually the cheapest option) is a good antenna. The "Dominator" is just a somewhat strange way to make a J-pole - it works just the same....
A J-pole is a ½-wave end-fed vertical, with a ¼-wave matching section. It efficiently takes your unbalanced coaxial feed and does a huge impedance transformation to feed the end of the ½-wave. It has a very slightly rising radiation characteristic, and is truly omni-directional (as long as it's in free space). It's a good idea to wind 5 or 6 turns of your coax into a coil of about 6" diameter, about a meter below the feedpoint to prevent RF coming back down the skin of the coax. This is an RF choke (NOT a balun as it is often described by people who don't understand aerials). I usually just wind some of the feeder up and either tape it into a coil (or use cable ties). I usually strap the choke to the mounting pole.
The J-Pole presents a DC-short to the transmitter - this allows a quick continuity check to see that the coax is unbroken, and provides a useful degree of lightning protection.
You'll find that the field strength from a "Dominator" will be
exactly the same as a J-Pole, and the "Dominator" is really expensive.
I used to make J-poles out of almost any pieces of metal I could find. I've even used the top of scaffolding with a ¼-wave stub strapped to it as an "improvised" J-pole! You can build them out of any old junk, and there are calculators on line to give you the dimensions for your frequency of choice.
https://m0ukd.com/calculators/slim-jim ... alculator/ works fine. With very little work, you can get a really low SWR!