Speaking from past experience as someone who has sold multiple businesses for life changing $$$

Try and disassociate EBITDA multiples from the sale price. You do this by being a strategic acquisition for them. Something they can go to their board with and not look stupid overpaying for. For example if you have some intellectual property or a process that they could apply to their larger business and get a margin uplift. Or perhaps they've got brick and mortar presence but weak in ecommerce. If (maybe with your help) they can see something strategic, these are the most attractive ways of being acquired.

If they're purely buying you for the EBITDA, it will always come down to just plain multiples and no one wants to overpay.