I'll start off by saying that I haven't read this whole thread. I started but had to stop pretty quickly.
As far as "non-numerical" price checks go, I'm a pretty firm believer in the idea that -- at least sometimes -- "merch" and "priceless" are the most accurate PCs.
If you really want to tie people's hands, why not have every PC thread be a poll? People could vote for certain price intervals (e.g., 0-1k (aka merch), 2k-10k, 10-25k, 25-100k, and so on). You could set it up so that the price intervals are adjusted according to whether the person requesting the PC indicates that the item is high-end, mid-range, or common. A tiered system would provide better "resolution" on the PCs (e.g., no need for low intervals on a high-end item, more choices ranging into thousands of armbraces...and vice versa for common items). The results could be shown graphically as a distribution at the top of the thread.
You could also make it so that the results won't appear until a certain number of responses (like, uh, 5, for example) from unique users are collected. That would lessen the impact of the first PC, which always seems to carry undue weight.
I just think people have to get over it. PC threads have always been a mixed bag at best. If you ask people for opinions, that's what you're gonna get.
EDIT: I just skimmed back through the thread and noticed that OS T proposed an idea that's similar to this one in some ways. Seems like a reasonable way to go if the goal is to strip people of the ability to use their words.