+1........Great, practical advice.
After forty + years, and owning dozens of guitars and basses (including several vintage Fenders), I'm down to two. A '95 MIM Jazz which I bought used for $125, and a recently acquired Squier Jag Shortscale. The Jag is now my gigging bass. It's great!
My main criteria is:
How does it feel/play?
Is it assembled well?
Neck straight? Other parts line up well?
No obvious flaws?
How does it sound?
If it passes these tests, I'm good to go with it. Even if the tone isn't exactly what you want, a pickup and/or wiring change will usually get you there. I can't see me ever spending over $1000 on any bass now, unless I hit Powerball, and then I'd probably get a Sadowsky or another vintage Fender just because I could!
So, don't worry about MIM, MIA, or Squier on the headstock. Find one that "speaks" to you and go with it. IMHO