alright, first you need to separate the gun into two pieces. Start by holding down the orange button on the right side of the gun. While you hold down the button, on the left side of the gun, turn the metal lever in front of the safety 90 degrees clockwise. The orange button and the lever can now come out. Hold the gun like you would cock it except pull them apart. Now the barrel and the trigger should be apart. The way daisy put this gun together makes it hard to remove the spring and the spring stopper. You will need two screwdrivers, first you need to separate the spring and the spring stopper. While one screwdriver pulls the spring towards the barrel, put the other in the back of the spring stopper and pull the spring stopper out from the bottom of the tube that holds it. ( The plastic is weak and should bend without breaking. After the stopper is out, all you need to do is pull a small bit of the spring out then spiral the rest of it out.
most spring airsoft pistols cost about that... but if it's a used pistol than it should be about 10
No. Wrong size.
It means it's not powered by electric or CO2 if it is spring powered you have to cock it after each shot
yes, you have to pull back to tense the spring. EXAPMLES: pulling back on slide on a pistol pumping the grip on a shotgun
In a gas there there is no spring, it is more like a real gun but with gas instead. In battery/electric there is a spring but It resets itself after every round unlike a spring pistol where you have to cock it every time.
I assume you are asking about BB guns not Air soft guns. There are a few that fall under $50 but they are C02 not spring powered. Marksman makes a line of spring pistols under $50 but they are terrible and not worth the cost. See the link below for C02 air guns.
Tactics and practice
No it is not possible