I am not really looking to start a recording studio but just having that space with some kind of solitude has been something I have been considering for a while. I have researched about sound curtains but they can be a bit costly too. A friend also suggested using sound clips because they have been proven to be an effective method. Are there any other cheaper options?
I don't think there are cheaper options than the clips. Unless, of course, if you can get used panelings. Anything used will be cheaper than new, and if we're talking about soundproofing materials, how "used" can they be?
Yeah, with the exception of used materials, there is no cheap way out of a good soundproofing. If you have a home studio especially, it's worth the cost though.
I've never heard of the clips you mentioned and I can't say that I've ever built a sound booth for recording music, but I have needed peace and quiet like you OP and the cheapest solution is to get a set of noise reduction earmuffs like you'd see at the shooting range or on one of those touristy helicopter attractions. They work amazingly well and you should be able to score some for less than $20.
Find a room with no windows and make sure there are no cracks in walls, doors, etc....This is the first step you don't hear much about, and those steps will help whatever else you do "work" better.