Unfortunately you really mostly have to visit stores, no-one will tell you their stock over phone. Mostly when you visit they will in the beginning tell you "no we don't have" but then open up the safe and offer you something nice if you're lucky
Rolex is indeed the best brand for "beginners" imo since the watches are obtainable for a lot more people than a Patek E.G (10 - 12k compared to 40-50K RETAIL). Rolex still has a huge demand and since most people are impatient and want to buy the watch ASAP (e.g IB people when bonus season is coming) Rolex is the way to go to get started!
Unfortunately if you're just starting out getting into watches (mostly steel watches) might be a bit difficult without any relationships, it's still doable but might take some time (realistically 6 - 12 months I would say with your local retailers, can be faster if you're lucky E.G on vacation).
Of course you can go the "fast route" with Chrono24 but you will pay premium, you can maybe find some good deals but all "professionals" will do their best to get their hands on those offers first. (Most good deals indeed don't take place on Chrono24 but B2B or in groups)
You can browse other platforms depending on where you live and make some good deals there but you really need to have some sort of expertise and do proper DD since fakes quality has significantly improved over the last years.
For 400-500$ from
China you can get watches I probably couldn't tell the difference and I have had quite some authentic ones of them. (Even watchmakers have their issue and they need to open them up to check on the movement since this is still the "biggest" tell) Don't be fooled warranty cards and invoices can also be easily be forged nowadays.
If I were you and just starting out, I would visit all "stores" in my area and come well prepared.
Tell them precisely what models you're interested in (best case one model) and tell them you want this watch for yourself and you're aware of the market situation. (Making a good appearance and being genuine and nice to the staff will definitely help you)
See their reaction and get a "feeling" for your local market, then decide how to proceed.