While I've never bought their food-safe PLA specifically, I've had good luck with other products I've purchased from filaments.ca, for what it's worth.

There are filaments with stainless steel or other metal powders that shouldn't rust (brass/bronze/copper are also common). The one I linked was just the first one DuckDuckGo spat back at me this time. Depending on what kind of sensors you need this to show up on, there are electrically conductive filaments that might also be useful to you.

As mentioned by another poster, Prusa is a pretty decent company known to produce reliable printers, if you're looking to start with a smaller unit under $1000USD.