There are many official KPop badges that are available at different events ready to be bought by fans. Of course there's also a variety of unofficial ones made by fans themselves. This is one of the example of a high quality unofficial items that will be definitely up your alley. It is a metal badge that depicts the official light stick of Pentagon. The Uni Bong - that's how it's called - was revealed for the first time in November of 2017. The item was released officially on November 23, 2017 at the Mini Concert Tentastic Vol.4. The fanlight was named after the official fandom of Pentagon UNIVERSE. It is manufactured by 101 Experience company under the license of Cube Entertainment.
The Pentagon badge you are looking at right now is almost perfect representation of the Uni Bong. It is painted in dark blue and light blue. The size of the item is 30 x 22 mm (1.18 x 0.86 inch). It comes with one sheet of paper with the name of the group on front and a barcode on the back with words "Made In Korea".
If you prefer the official items - which probably will be a little bit more expensive - you can always try to get them online. They show up from time to time but are immediately sold out. The official ones were for example included in the selection of goods commemorating the debut of TXT (Tomorrow × Together) titled Hello Nice To Meet U!. Three versions were available - Star Album Ver.1 consisting of two plus signs and one multiplication sign, Star Album Ver.2 with two pairs of hands and Tomorrow X Together version featuring the name of the group. Mamamoo is known for the badges they include in almost all of their merchandise collections. The badges represent many of the group's albums. There are the badges released for Mr. Ambiguos, Uhm Oh Ah Yeah, Piano Man, Memory, Melting, Purple, Red Moon and Yellow Flower. During the first concert of Taemin titled OFF-SICK in August of 2017 the fans could purchase one of two available badges with the title of the event (a rectangular or a round one). A new badge with the name of SHINee member showed up at the encore concerts OFF-SICK On Track in November. Additional two was available at his second solo concert in 2019. You could complete a nice collection of 19 different pieces at the NCT 2018 Fan Party! (Spring) fan meeting with the group's fans that was held at the Korea University Hwajung Gymnasium in Seoul. Four cartoon badges was prepared for the Chung Ha'ppy Birthday Party & Fanmeeting of Chungha that took place at Yes 24 Live Hall in Seoul on February 3, 2018. The set consisted of a cartoon character depicting the singer, a cupcake, a piece of cake and a puppy.
The badge was manufactured in South Korea and is available from the seller based in Seoul. You can get it for only $10.74. It is a very reasonable price for such a nice item. The seller offers the badges of other KPop artists including Twice, Stray Kids, EXO, VIXX, Red Velvet, GFriend, Seventeen and Blackpink.