Definitely a great find! That color combo in that size is top of the line for flow. I think you will be very pleased with it for a long time to come!
Being a screw-on cap, this may predate the Midnight Aristocrat as such. I think the lamps released as Midnight Aristocrats were all after the change to bottle-cap tops. The only screw-cap black Aristocrats I've seen (aside from the 1971 Commander series, which had a matte finish) were the yellow/blue and yellow/violet ones sold exclusively through Target for a short time in the mid-1990s. If this is one of those, $5 is an amazing price!
Hope your party goes well, it would be great to see some photos. Is that 17 lamps for years !