Hey,
I am getting my middle son ready for boy scout camp where he is going for his rifle shooting merit badge.  Since I am a boy scout instructor for rifle shooting merit badge, I had to make sure my kid can make it.
I have an old piston cocked Ruger air rifle which was big, heavy, inaccurate but cheap to shoot.  My older son and daughter learned on it well enough to earn a rifle shooting merit badge (former) and take down deer with neck shots (latter) but couldn't group for shit and was really too big a gun on weight and LOP for kids.

So I got the 1077.  This is a CO2 powered gun that is well under 1 inch at 10M (10 shot group, first time shooting it prone unsupported).  about 40 shots per cartridge.  I sprung for the expensive german pellets (will compare to crossman pellets later)

For a 60 dollar airgun it is very accurate.  sights aren't the best and the trigger is HORRIBLE.  However, that just means you have to apply the fundamentals even more.  If you train on this and then go out, I guarantee you will see better shooting from beginners to intermediates.  As I am not an expert on marksmanship, I can't judge how it will affect.

So I spent 80 dollars on a new air rifle, pellets and 20 cartridges.  Money well spent.