You can eat for free or with cheap money/cheaply.
I'm finding 安いお金 a bit strange. If I wanted to say "You can eat for free", I'd write:
If I wanted to say "You can eat cheaply", I'd write:
Are these both correct?
安いお金で reads to me like "with cheap money". I'm guessing you have to do this because
is ungrammatical (at least it looks ungrammatical to me). It's hard for me to see how you would get from 安く食べる to 安いお金で食べる. Is there are more general grammatical transformation going on here, or is it just specific to this example. If there's a more general principle, could you give some other examples please?
Maybe my most general question is how do you say
(adverb A) or (adverb B) verb e.g.
Run quickly or slowly (you'll still get there in the end).
or maybe that's totally unrelated to the problem above. Sorry for rambling.