Jenn, Weston is on pulmozyme, right? The clinic should give you a Pari LC Plus, that's what they gave me when Vinny was first put on pulmozyme. They also gave me a Pari Vortex holding chamber for the inhaler, it hasn't melted, maybe they can give you one too. I have a duck mask that hasn't melted, but the Pari bubbles the fish mask did, I'd take that out sooner.
You can try putting them in a bowl of water in the microwave to boil too, that's what I do now. Or if your dishwasher has a sanitize feature and gets hot enough, you can use that. But I agree, the sterilizer sounds like the easiest way to me, I want to get one soon.