You'll get a much better workout at the gym at a cheaper price, assuming that you're not about to shell out thousands of dollars on gym equipment to use in your house.
However, I've moved from going to local & university gyms to walking down to my basement with multiple pieces of equipment. This includes:
- A power rack (~$400)
- Pulley system (~$130)
- A barbell (~$160)
- 400lbs of weights (~$260)
- A pair of chrome dumbbell handles (~$60)
- Shitty dumbbell steel weights (~$80)
- Horse stall mats (=$150)
- A chinup bar (=$30)
- A few other things, like a treadmill, elliptical, etc. which really don't add much to a workout. Don't get crap for cardio if you really don't have to (~$6500)
The first six pieces of equipment are probably the bare minimum that you'll want to get if you want to lift with the kind of satisfaction that you'll get with a gym membership. That brought me to about $1300 without factoring in any of the other crap that I bought. This doesn't even come close to any of the extravagant setups you'll see on
the homegym subreddit, made by people whose dedication towards fitness is on a whole new level.
If you can follow my math, the equipment would have paid for itself after 2 years ($60 x 12 x 2 = $1440).
Long story short: don't invest anything too big into fitness until you can ensure that it's something that you really want to get into. I know that you're not looking to get fat (or bulky, or whatever you want to call it), so just go for a gym membership. It'll probably total out to be a hell of a lot cheaper than the amounts that I've put into bettering myself. I don't know, go for a one-week trial, try it out, follow a strength routine, eat well, and see if you like it.
Good luck.