totally agree that some prices are really not logical
tbh im buying all sledge hammers and spears from npc, sometimes to craft but its also worth to buy and science, almost free science skill and resources
while some other items like chemical components are too expensive
you can also buy laser pistol for 50, upgrade to magneto laser only for 1x EP 3x MP, get xp, get skill and sell for more, same with sledge hammers->super sledge hammers
some of prices should be really changed