A reply is not a deal yet, and the next message decides which way it goes. There are only three replies you will get.
"What's your rate?"
Give a number. Deflecting — "what's your budget?", "open to anything" — reads as someone who has not done this. Before the number, two quick questions are fair: what format they have in mind, and whether it runs on their channels or yours.
Then a starting rate, and the note that running it as a paid ad is priced separately. If it came in a DM, keep the number to a starting point and put the full quote in the email, because rates typed into DMs get screenshotted and forwarded without any of the context.
"We can send product"
Decide on four things: would you have bought it, do you want a relationship with this brand, does the content fit what you make, and is the ask small. If all four are yes, it is a fair portfolio play. If it arrives with the deliverables list of a paid deal, it is unpaid work.
Either way, put the paid option in the same reply. "Happy to do this one as a gifted collab, and if there is budget for a paid piece next quarter I can send a rate."
And if it's just "Yes"? Before you film, four things go in writing in the email thread. What you will make. The price. When it is due. What they can do with it, and that the usage transfers when they pay. Three sentences is enough. Every messy deal you will ever have starts with one of those four being assumed.
Then log the reply so the deal lives in a record instead of your DMs.