With your budget a decent fork is a bit " moon on a stick" I'm afraid. The Suntour XCT fork on your bike is notoriously budget end of the spectrum. They don't damp well, and you'll be lucky to get full travel out of it anyway. A decent fork is a worthy upgrade, but you'll need to be prepared to spend a bit more to get what you want. You also need to know what you've got on it at the moment. There are many variables, such as steerer length, length of travel, axle standard, steerer diameter etc etc. The frame looks as if it has a straight 1 1/8" steerer and 9mm qr axles, so that's a start.
You need to match travel front and rear, although a 120mm travel fork will fit, the it will alter geometry and the handling of the bike. Be careful you don't void any frame warranties. It could theoretically turn it into a pig of a climber, whilst improving downhill.
How squishy a fork is depends on the spring. You could buy a quality coiler that will be better than a crap air sprung fork, but Suntour do the Raidon air fork which isn't quite double your budget new. They review well.