Personally, because as I get older I tend to get injured (more fragile) easier, and because some injuries were caused by trainers who were not certified and may not have used the right approach when I was younger, I am now paying the price because of lack of proper knowledge and moves I should have avoided or not do so many reps.
Because of my own experience, I would no longer seek a personal trainer that has no certification in sports. Yes I could take in some of the experience, tips and tricks that a non-certified person has but that would be about it.
The one I currently have and go to for the past few years is a physiotherapist and kinesiologist. Being also a triathlete and involved in many sports, she knows how to prevent or treat an injury and when to push/pull my buttons!
And my trainer is not charging more than a non-certified trainer I am sure (for me it is about $80 per visit and we exchange almost daily through emails, training peaks for my program or a quick call for follow-ups until next visit). And I get receipts to be reimbursed by my group insurance and the gym program we have at work.
I think it is important not only to tell people how to move and improve but how to do it safely and when an injury occurs, how to balance the whole thing and heal as quickly as possible to resume training. A safe move for one person, can be the worst one for another one. I think qualified trainer are/should be able to see that difference.
I don't know where you live but there must be insurance liabilities to deal with as well. A signed discharged is not always getting some off the hook. I think certification protects (at least we’d hope) the trainer and its clients. They are based on many measures. Someone may have a good deal of knowledge in many areas (health, physical, etc.) but to me a good certification is essential.
There are so many people calling themselves personal trainers now and some are good and some are bad. Overall, I think it's up to us, consumers, to do our own research, look into backgrounds, and find a skilled and qualified trainer. Not easy.
There will always be expectations and you may find a pearl of a trainer that is not certified.
So yes…I think you should save money somehow to take classes and get a certification if this is what you truly want to do with your life. You maybe ok like that someone you know…but what are you looking for: doing ok in your business…or being the best trainer you can be for your clients and for yourself.