You may already own a Bluetooth speaker or two, but can it plug into a guitar, be used with a mic for karaoke, and wake up your neighbors a few doors down? The JBL PartyBox 200 sure can, and it's currently $50 off at various retailers.
JBL markets the PartyBox 200 as a party speaker, and with different "light show" modes, 2x 6.5" woofers, and 3x 2.25" tweeters, I can see this 33 lb monstrosity filling up a room with music — it's rated for up to 120W of output. For audio input, there are the standard options like Bluetooth, 3.5 mm aux, USB, and RCA, but guitar and mic inputs are also available. The speaker lacks an internal battery so it will have to be plugged in at all times — though it does accept 12V DC from the included car cigarette charger, and can be connected to a 12V battery.
Originally $380, the speaker is currently available at a $50 discount, though I don't know if this is a permanent price cut or just a sale. You can pick up the PartyBox 200 from JBL, B&H, Newegg, or Amazon, where an "Amazon Renewed" version is available for $290, an extra $40 off.