I can't help on the chat front, but there are plenty of Mardi Gras/Carnival/Masquerade/Venetian masks for men as well. Click me
for some examples. I'd suggest finding a store or site that has reasonably priced masks w/ free or low cost shipping for men AND women, and perhaps getting a couple of complementary sets of masks. Then you'll both have at least one backup option if a mask is damaged, or even if you just want some variety.
Sets of Halloween/Costume masks would be another option, and might even be a fun/sexy element on its own. For instance, you could do a couples' superhero mask (and even costume) set and add some roleplay [elements] into your cam sessions.
Yet another idea is makeup/facepainting, particularly if either of you have an artistic bent. That would be great because there wouldn't be any separate masks to worry about shifting out of place, falling off or being uncomfortable in the heat of the moment. Plus, I think the application has the potential to be a fun, creative, intimate activity on its own - possibly a very interesting form for foreplay, if you will. Anyway, if breasts, asses and bits can be disguised with bodypainting, you could certainly obscure your faces with makeup/face painting. While elaborate painted-on "masks" would probably be impractical for frequent play, they could certainly work occasionally, or you could go for simpler versions more often. If you don't have inherent painting abilities, check out some of the free video and other tutorials on face painting online. Or, hey, you could always paint yourselves up as clowns!
Ski masks and the like are certainly options and probably offer the highest level of privacy and safety (in terms of staying in place and such), but I'm guessing a lack of comfort would come into play because they DO work well for trapping heat. Plus, you and your partner may not find them particularly sexy unless you're doing some sort of ski-masked burglar or whatever role play.
You'll also want to think about concealing any identifying marks, like tattoos, unusual scars or birthmarks. There are heavy duty makeups that are extremely sweat and water-resistant for that sort of job.
Hopefully others will be along to give you ideas on free/cheap cam sites, but the above should at least get you started on thinking about your mask options!