Hi David,
First of all you need to keep in mind that paid directories may be able to take your money, but they can never take YOUR FREEEDOOMMMMM!!!!!
Now that I've got that out of the way (and hopefully delivered a mild chuckle at least) on to the business at hand.
There is a fundamental problem with "paid" directories. That being they have 2 options when it comes to the links they provide from their directory listings. They either need to 'nofollow' the links to not have Google penalize them as a link buying service, or they need to hide the fact that they are indeed basically just a link buying service... otherwise Google will likely penalize them.
You need to look at a paid directory from Google's point of view. If the directory is openly advertising that you can pay them for inclusion, and thus get a link from their site for the money then Google has just about no choice but to flag the directory as a link buying service.
If the directory already links to your site for free as a service to their customers, Google can consider them a legitimate service and not penalize the directory. Many directories of course do this and then offer premium type services that business can pay for and not receive any Google penalty from (yelp and even the BBB being great examples). In this case, though, you're not really receiving any extra "link juice" for the service you're buying. You're usually just receiving extra visibility or an endorsement of some sort.
So in short, if you're trying to find a paid directory for the purposes of acquiring links I would strongly suggest you rethink your strategy. If you are, however, simply looking to "buy links" then disregard this advice.
EDIT - Something I realized I need to add. You stated you do recognize that BotW rarely shows up in back link reports. Site's such as BotW and others (JoeAnt and so on) I think don't pass much link juice through to websites from Google and Bing. The search engines recognize that these sites offer paid review services, and while it's certainly not like link buying because instead there are editors supposedly quality checking the URL's submitted, I would guess the search engines still do not pass full link value on to websites.
I could be very wrong of course - I've just never seen any noticeable impact from going through directories such as those.