a/c leak sniffer purchase advise

[James L]

I want to purchase a haloginated electronic a/c refrigerant leak detector (sniffer) to check for leaks instead of dye. I noticed they range in price from $50 on up. (about what i would pay a shop to sniff). Brands I have seen (all have the flexible extension probe and battery operarted);

TIFXL-1A, CPS L-780, VIOT HLD-7, INFICON TEK-MATE new and used.

Thanks