2-problems, I can offer my experience on BOTH!
Antenna alone will more than eat up yout $160 budget. aftermarkets have yet to produce a good antenna that doesn't rattle or seem cheap as you say. If you need an original antenna, I have a new extra one I may part with (but I will not 'give' it away, I just watched another NOS one sell at about $200 last night for a clue)
2nd, my 8-track did the same on one side. Short answer: Cannot be fixed cheap. I had mine at a friends house who does electronics for about 6 months, though he did work on it (I even gave him a copy of the schematics), he said only way to really assure no trouble was to re-work the whole circuitboards and many of the parts within are not really readily available in the modern world. I am sure there are repait shops that can fix it, they are out there but I doubt a "budget" ought to be set on making it happen. Conversion work happening all of the time where you have new innards put into it. Cheaper and more reliable is what they all say. AND you can ask for upgrades! (FM, i-Pod MP3 inputs, Bluetooth...it goes on and on!)