I think that you dont need shield, X and Y axis is not too close, and dont have another ferrous metal part around inside stick.
Anyway, since you disassemble a defective CD/DVD-ROM drive (to get magnets) these things have a small DC motors, disassemble one - leave metal case and internal ferrite magnet - and use around your HALL assemble. Sample:
Clarification to CH purists: Tirta no making any sacrilege putting HALL in your Fighterstick.
Are a old gameport model "USBbified" with DIY Mjoy16 controller.
BTW - Cost to replace 2 CH pots ~ 20 U$ + 10 U$ postage (last time I buy. And in my case + country fees, around 100%).
Cost of DIY 2 HALL + magnets assembly ~ 10 U$.