If I only buy the GSA search engine, will it work?

Search Engine Ranker has so many functions !!

You can continue to explore for a while and find new things.

Even so, the other specialized GSA tools that I now use are very good at what they do and work amazingly with SER.

Sven is the person who wrote the software, ETradeSupply, in case he did not know, so he knows better when he says that it really is about what his goals are. It is a very versatile set of tools.

As you grow and learn with SER, you may need one or more GSA products such as Captcha Breaker, Content Generator, Proxy Scraper, SER Indexer or even complementary engines. (although you can even write your own engines with SER!)

You could do a lot on your own. SINGLE with BE, and many people probably do.