Can I be held to a price I only agreed to informally in an LOI?

Generally, no. Price is exactly the kind of term LOIs for a business purchase and sale are typically drafted to leave non-binding, precisely because it's expected to be revisited once due diligence, financing, and legal review are complete. A number written into an LOI usually reflects a starting point both sides are working from, not a locked-in commitment either party can be held to later.

The exception is if your specific LOI departs from that normal approach — either by explicitly stating the price is binding, which is unusual, or by being drafted, or behaved toward, in a way ambiguous enough that a court could find the whole document, including price, was intended to have immediate legal effect. This is exactly the kind of drafting mistake that catches sellers off guard: assuming a number is "just for discussion" when the actual language doesn't clearly say so.

Rather than assuming either way, check whether your LOI expressly states that price and other commercial terms remain subject to a definitive agreement — clear language like that is what actually protects you, not just the general expectation that LOIs work this way. A Treadstone business lawyer can confirm exactly what your document says.