I'm going to use flowers as an example again (its just the easiest to explain).
Brides: Be specific and don't be nervous about giving an amount. Let's say you've determined that you have $3,500 to spend on all your wedding flowers. However, you would really feel more comfortable only spending about $2,500, because you really want a cigar roller. Tell the florists you meet with that this is the case,
"I have a maximum budget of $3,500, however I prefer to keep it under $2,500 if at all possible. Any suggestions you have to keep me under this price would be greatly appreciated. But if it's going to compromise the integrity of the designs you have in mind, by all means say so and we'll go from there."
It is so helpful when you ask for a budget up front in the consultation, not at the end. That way you can only make suggestions along the way that are going to be possible. Also, if you're going to make suggestions that are available in a range, show/explain what the range is!
"A centerpiece like these photos you brought are going to be in the $75 to $200 range. $75 would get you roses in a shallow 5 inch vase like this, $200 gets you Cymbidium orchids in a celebration vase like this. To get it in the middle of your comfort zone, we could put the roses in a celebration vase."
Here are some other read worthy budget posts I've written.