Hubspot is still indicating that the “dedicated IP” is the only solution for $3,600/yr.
“You need a dedicated IP to have a custom return path - this is why you and other members of the community aren’t seeing it outright available in marketing hub professionals. Dedicated IPs are an additional $300 per month, you can purchase it through us at HubSpot and HubSpot would help monitor it for health.”
I argue that other email heavy products can do SPF without dedicated IP’s and additional costs. It sounds like Hubspot might be willing to discount the dedicated IP if we push hard enough, but there was no indication that they will have a fix for this anytime soon. If this is important to your security teams, then you’ll have to commit to the extra cost or find a different solution.