If you find them for less than 20$ buy them.

I found mine for 15$, wouldn't bother if I found them for more (as the price tag suggests). I already have Koss Porta Pro and AKD K-55 that have better sound.
But for 15$, they are more than OK. 24 ohms means they are easliy driven by all possible equipment that have phono output. Bass is fine, but the overall sonic picture sometimes needs to be adjusted with equalizer settings. Don't be fooled that RP-DJ100 are Pro DJ headphones, they are just entry level for kids who want to be DJs. But for portable use, these are more than adequate. They are also foldable for travel.
If you find them for more than 20$ go for Koss or AKG budget series, but if you find them for less than 20$, buy them!