Sounds like a Potion of Bull's Strength juiced with the Rage spell. Whether your "Potion" is a liquid or a bunch of leaves is strictly a matter of "special effect".
Now I think that +10 strength is a bit much, but combining those two will get you a +8, and a temporary CON boost as well. And because the Rage comes from the spell, there's no period of exhaustion or fatigue afterwards.
So, as for the price, there are already rules for combining multiple spell effects into a single item. And since the two effects have similarities, and a potion doesn't use a slot, you get a discount on the second one.
So start with the price for a 3rd level potion (Rage), 5th level caster. That's 750. Add in 1/2 the price for a 2nd level potion (Bull's Strength), same caster level, which would be 250, and we come up with a nice, even 1000 gp for a 5th level potion.
This would have a five minute duration (which is why I suggested 5th level caster for the Bull's Strength) instead of ten, but fifty rounds of maniacal strength and durability seems like plenty.
That duration is far longer than the Rage spell, which is Concentration + 1 round per level, and far longer than any Barbarian rage can ever last.
Five minutes of being Superman seems like plenty. If you want to cut the cost, cut that duration.
