I totally understand the pricing issue, and I think a rough estimate would be perfectly fine, even if they were rounded. A "price range rating" might also work, e.g. $, $$, $$$, with each rating representing e.g. $0-99, $100-299, $300+.

The negated filters are mostly for when I would anticipate the list to be much longer, so that after you've decided which features you definitely _do_ want, you can say "this list is still too long to narrow down my choice, so I'll just check off a few features I don't necessarily want but which most assuredly would also affect the price".