Is it advisable to purchase a Birkin handbag rather than investing in equities? Generally speaking, no. A Birkin may qualify as an investment-grade collectable, but it is more appropriate for it to represent a part of an investment portfolio rather than an alternative.

In particular, rare Hermès Birkins that are in very good condition may be sold at an attractive price in the secondary market, depending on the bag's size, leather, colour, hardware, origin, and any accessories that might add to its charm. Return on investment appears to be uncertain. 

In addition to this, the resale process involves considerable time and costs connected with storage and maintaining the bag. Equity trading usually features higher liquidity and allows for diversification.

Thus, Birkins can only be considered a real collectable for someone who would enjoy keeping it for a long time and anticipates the possibility of getting the money back in future.