...Hmm....
Well a few things are true:
1) Orchestras - if they're any good - are expensive. Real expensive.
2) A lot of projects that think they can't afford orchestras, have more than enough money for one, if they deprioritize name-brand snack-cakes at craft services. But they don't, because 1) Everybody eats a craft services and 2) Nobody ever sees you until the film is done and wrapped, and 3) Did I mention how big a deal food is on a movie set?
3) Not enough of us push back against the whole thing. You gotta stand up and make that fight, which a lot of us won't because we're afraid of losing the gig. I've made more than a few conversions over the years through Academy-Award-worthy impassioned speeches and a few brutal side-by-side examples of virtual versus real. I've seen budgets magically go from $50k for music to $250k. At a certain budget level, it's in there. Doesn't mean they'll spend it.
4) Sometimes, you just don't have enough bread to do it all right, so you're calling in the favors. Do it sparingly, because that word spreads at lightspeed, but know that it happens and don't beat yourself up about it forever.
Just be sure to go a few rounds with the director - I told one once that a virtual orchestra is like a really good blow-up doll of your girlfriend; just 'cause it looks a lot like her, doesn't mean it feels the same. He actually went for it. So you never know. If cheese like that can instantly quadruple a budget, then don't fear going for it.
_Mike