You are not going to get a notable weight loss within your price range. You will get a far better fork, and a dropper, and one or two step upgrades in component quality. But it’s all durability or utility, not weight.
I have the base model Timberjack which was replaced last year by the Rangefinder. I like it a lot. I’ve since added a dropper (not included in 2018), replaced worn out tires with much better ones, and found a really great deal on a clapped out premium fork that was easy to fix. I’m not looking at any other changes right now.
The forks in this bracket are not light but especially avoid anything with a Rockshox 35 Silver, it’s a horrid boat anchor pretending to be a Pike