Linear Tracker ...I was wondering


Is there a not too expensive (less than $¹⁰⁰⁰) and good linear tracking tonearm that I could mount on my SL1200MK5? 


128x128jagjag
Be hard to find anything new for less than $1000. Unless you wish to take a chance on some designs from the UK?
Like this......
https://www.airprodigy.co.uk/

You may find a used ET arm for that price though.
Is there a not too expensive (less than $¹⁰⁰⁰) and good linear tracking tonearm that I could mount on my SL1200MK5?

Depends on what you mean by "good". If you mean one that works reliably and fits on the table then maybe, yes, you can probably find one. If you mean good compared to what the same $1k will buy you in a normal pivoted arm then sorry, no, but thanks for making me laugh.

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Your best bet might be to find a used table with a linear tracking arm and salvage the arm off it.