For the record my mum is a writer too and my sister has been a beta reader for others including a traditionally published author; they both know what is required from a beta reading and from the times Mum has read things I've written in the past, she's not shy about being pretty starkly honest.
You are fortunate in this regard. Although my comment referenced you, it was directed more towards the general writer who doesn't have relatives in the business. If it were me, I'd still be concerned about bias regardless of how slight.
So you might say "You can get your book edited by a professional for $600" but that might well be money very poorly spent when someone like me is equally qualified and experienced in proofreading or substance editing but willing to trade beta reads rather than charge for them.
True depending on what you're looking for. The editors I'd hire would have an established record of success with authors whose work I know.