Well .... if the crank is hitting the derailleur and you can't shift into the top ring .... Your derailleur is twisted.
If the rings are really worn ("shark-finned," where the teeth are shaped like cartoon waves) then you might find it easier to replace the rings, not the whole crankset.
A quick web search shows---https://www.modernbike.com/shimano-50-39-30-cranksets that you can get a Sora (
https://www.modernbike.com/shimano-s...t-not-included) for between $90 and $110 depending on crank length.
But .... the derailleur hitting the crank? That is a twisted derailleur, IMO. Not crankset wear.
I assume you have a threaded bottom bracket, in which case I would go with a Shimano Hollowtech II bottom bracket as well.