When feasible, I like to have two or more of the item I want to reforge. I start with the worst one. Soon as that item gets a good-but-not-quite-perfect modifier, I switch to the next-worst so I'll always have at least the "high point so far." This saves money in two ways: first, I'm rarely forced to endure long, costly series of upgrades to barely-okay modifiers, and second, it costs less to reforge an inferior item than one that's already got a good modifier.
In my experience (which is limited to pre-hardmode) this method is feasible for a Cloud in a Balloon, but infeasible for a Bundle of Balloons; feasible for a Blade of Grass but not for a Night's Edge; feasible for Spectre Boots but not for Frostspark Boots. I'm lucky to have got even one each of the latter items.