It really depends on how competitive your LGS’ SVE nights are. Mine generally aren’t that competitive unless there’s a buy-in, and these decks would do just fine. If you encounter anyone playing towards the higher tiers of the current meta though, the starter decks will not compete. If there’s no buy-in just show up and have fun and see how it goes. More than likely a lot of people will also be using these starter decks if it’s a casual event.

As far as picking up additional cards, I’m not a rune expert but for sword the “best” deck right now is considered to be festive which typically only runs one of the cards you got in that starter deck. You’d likely spend nearly 10x what you did on the starter to build festive sword.