An agency is an instant cashflow model business.

Ugly to scale due to logistics of a team and the mess of being in a client-service business model.

But easy to rapidly monetize.

Make a phone call. Close a client. Collect the cash. (Yes, that's a bit over simplified).

Your girlfriend shouldn't grab a dime from anyone before locking in her first client.

An agency can be entirely self-funded and there's little reason to pursue funding.

After she had generated her first $50,000 in clients (for example), she can supplement growth with debt financing.

And, in no way, is the idea of your generous, retiring parents investing $70,000 into a first time business owner, when statistically most businesses fail ... a good idea.

Fair rate is a flexible concept.

If I was lending out $70k, I'd want to see 3x $210k back as a minimum. Irregardless of whether that is "fair"... it would be the minimum (for illustrative purposes) where the process of the due diligence and contracts and parting with $70k liquid in trade for a "maybe" $140k gain would be of interest.