Could be. As far as i can tell they do not market themselves, word of mouth only work so far within their (German?) tech savvy audience. I was a student in Germany since 2003 and use Geizhals extensively for purchasing stuff, especially computer related stuff. Other price comparison engines like Idealo, Kelkoo etc. suck in compare to Geizhals.

Geizhals had a rough stance in Germany. Despite being very early on the market, it used the .at TLD (and later geizhals.cc and geizhals.net) because it was impossible to acquire the .de domain. It was later bought by a competitor who turned his deals website into a price comparison (geizkragen.de), which caused much confusion among german users. Eventually, Geizhals bought the domain (along with the .com, which it had gone to WIPO over and lost - https://www.wipo.int/amc/en/domains/decisions/html/2005/d200... ), for a (AFAIK) record-setting 7-figure price for a .de domain. Said competitor went on to build bitcoin.de and was very successful with it.