It's going to be tough getting into a PCP air rifle for $500 because you need other items in addition to the riffle to start shooting it which costs more money. But PCP's are a joy to shoot and easier to shoot well because of the almost non existent recoil. You'd need to buy a high pressure pump, or a scuba type tank, and or a high pressure compressor. Also maybe a fill adapter to fill from the tank to the reservoir on the PCP airgun.
Your Kodiak is known as a "springer", it's a spring piston air rifle.Your rifle "might" be accurate with higher quality pellets such as JSB brand. I'd try that first. Also it's important to place "everything" that touches the rifle the same way every time if you want consistent accuracy. Those Kodiaks are not easy to shoot because of it's violent power.
Possible your barrel is leaded up, scope mount or rings are loose, as well as the screws holding the action to the stock. Check it all.
Michael, you should start a sticky on this subject.