You never know, but I have always shopped around and found some good buys on NOS and pre-used batteries. I bought a batch of out of date batteries a few years back. It was 15 batteries and a couple chargers for $200. About half wouldn't hold a charge for more than an hour or two, but some seem just like new and are still going strong.
If you search around, you can find places selling off quantity lots of the whole PAPR systems as they age out, (unfortunately, usually sold without batteries). Buying a lot of six to ten Breath Easy units with carry bags and the paint booth/pharma lab disposable type hoods may only cost a couple hundred bucks. You can chuck the hoods in the trash, sell off the extra five or so blowers for $100 each, but some batteries, and buy a 3M hood type helmet and end up spending nothing in the long run. I have also found the filters in large lots for next to nothing. They are usually sealed but out of date, and can't be used by OSHA shops/labs, but are perfectly fine (after all, they are just filters).
