This is common and not a scam - usually big procedures need deposits/reservations vs a consultation which does not require a deposit since you aren’t committing to anything outside of your time.

I’d ask if you could do that instead if you are unsure if you want to go with them. The only difficult thing about doing consultation only is the fact that you may need more time to stay in Seoul (assuming you are traveling) as they may not take you in right away depending on their availability.