Brickforge is what you want (combined with some BL orders for minifig body parts)! They have got all you need - shields, helmets, swords, plumes, stick 'n' peel decals, etc. and it looks goood!
Now if you are willing to spend the money, you can't go wrong with Brickforge.
If you don't want to spend the money necessary for cool minifigs, props and sets, I would rather advise against making a Roman-themed film. Of course, it depends on how good you want the final result to be BUT if you're planning on putting some real effort and hard work into it to make an awesome film (for example reshooting scenes until animation is flawless, getting rid of all the light flicker, making realistic sets, etc.) then I don't think the film is really going to shine without proper minifigs. In that case, I would rather make a film that's not so difficult to pull off properly (with less unorthodox minifigs and props in general), and make that one as good as you can.
If you don't want to take that much of a hassle with your film and are happy if it's "rather good" (that's perfectly fine), then yes of course you can take cheaper-looking minifigs sans problèmes.
I would say it all depends how serious you are about your project, and where your ambitions lie.
PS: After having watched parts of your TOY film, I think your films will look much better if you put more emphasis on backgrounds. For example, you could experiment with chroma keying (blue/green screen) a bit. Painting your own backgrounds is also something very much to consider - I'll try that, too, soon. And you don't need to be a great artist to do it, the ability to hold a paintbrush is enough for most generic backgrounds.
(if that was all gibberish that doesn't interest you, you had better stopped reading after paragraph 2!
)
-pacific