Bags are not investments. The whole "investment piece" phraseology in fashion means, basically, that if you "invest" in something classic, it will return its value versus a bunch of trendy one-season items - it does NOT mean "put your money in bags instead of in the bank or the actual stock market". The Birkins vs. gold "study" was done by a reseller. Can you profit by owning and then reselling Hermès? MAYBE, if you buy a popular size and color that stays popular and you never or barely use it. Stocks are way, way easier.
If you are looking at a wardrobe piece that will hold value, Chanel does pretty well, but the quality IMO keeps dropping. I'd go Hermès every time.
To answer the OP specifically:
- if the money will never be needed and is pure spending fun money, buy the bag you love from anywhere unless playing the market would be fun for you.
- if the money is not needed right now and very unlikely to ever be needed, I'd put it in the market, but if you really want a bag, I'd get a good deal on Hermès.
- if the money is not needed right now but you could see needing it someday, I'd put it in the bank, BUT you could think about a low-risk portfolio buy in stocks/bonds.
- if the money is at all meaningful to your life today in terms of paying the bills, put it in the bank
