Ok guys, I'm new here and new to mountain biking. And when I say new I mean I've never been. so here's my story and I need advice. I'm a crossfit instructor here in Ky looking for a new sport to try. So some guys and I decided to try mountain biking so here a I am. I have a cheap bike that I believe came from target, It's obviously not gonna cut it so I'm gonna upgrade. My problem is money, I'm not ready to spend a lot right now. Ideally I'd like wait till Christmas and get a nice bike. Plus I'd know more about it then and I'd know if I'm gonna like it or not. I'm willing to spend $150- $200 right now to get started. So do I upgrade current bike? Buy cheap walmart bike? or just make due and save my money til I can afford what I want? I'd really like to get started but I honestly don't trust the brakes or gears on this bike. I should mention that I'm fairly mechanically inclined and I work on my own cars, motorcycles and (I hope) bikes. I do however have enough sense to take it to a pro if it's over my head. But I would like to learn to work on my own stuff. To me it's part of the fun. Thanks guys, any help or advice is appreciated. Even if it's not an answer to the questions here.

Rusty