I'm a high school sophomore, and I've got a bass that's been sitting under my bed for the past year. It's an RJ, which is a local brand here in the Philippines. I've used it at gigs and jam sessions, but after some time of using it, I'm starting to hate the sound it makes. Plus, it's falling apart pretty badly. (The tone knob is broken, and the internal components were literally built right under the pickguard.) I'm not really planning on buying a new bass, so I'm just thinking of modding this thing like crazy. I'm a bit new to this modding game, and I'd like to keep the modding cheap, so any suggestions?
I also have a bass that has it's components stuck on and under the pickguard.
With how you're describing your bass, it seems like a better option to just buy a decent to low priced bass. The cost of parts and the time it takes to actually replace the bass is probably going to cost more than buying a brand new one.
If you're planning to customize and mod it, I suggest you find someone with experience and is capable of doing so.
Cheap parts are cheap, and it isn't going to change.

Go buy a new bass instead.

And you learn so much by modding it yourself. It deepens your relationship. "Hey Jude..." etc etc. You'll love your guitar more (assuming you dont destroy it ;-). Modding and tech skills should be valued by all players, but many ignore it. Messing with a cheap guitar makes you fearless.