I’m new to collecting pokemon cards and got a question.

So just started collecting pokemon cards, went into my local card shop and bought a 151 zapdos collection. While in the process of purchasing the collection box the cashier told me that the 151 is hard to find and if i found any to buy them because they pokemon stoped printing for 151. Is this true? Should i buy another type of packs or should i stick with buying 151 packs?? I went to buying 151 because as a kid i remember playing original pokemon red and blue so the first 151 are the only pokemon i know on the top of my head.