Only for the 20% off sale, IMO, and then only if you have things you need/want right now. I wouldn't waste $50 to get VIB.
And even so, sites like dermstore.com, spalook.com, skinstore.com, and beauty.com often have 20% off (or similar) codes/sales that are open to the public and they sell a lot of the same stuff as Sephora, so a lot of stuff can be gotten at a discount even if you don't shop at Sephora.