I checked out one of these -- essentially, the plans were scans of the magazine plan pages, and really bad ones. Plus the 3-views had been scooped from the Russian 3-vview website.
I've also looked over the plans that are available on eBay. If they are from a small list of dealers (who shall remain unmentioned but a little research will find them), they are illegal copies (run down to Kinko's, get 20 copies of the plan and glog the copies).
For what it costs, dealing with the publisher's plan service is always better -- magazine stays in business (yes, advertising pays the bills) and they have the incentive to print and sell plans. Magazines are slso getting smart about their plans -- free copies with the issues (great!) or are blocking out sections (RCM did this for the last few years -- enough to decide if you wanted to buy the plans).
For what's on the web, well, a lot of what I've seen is the same as what's on the CD-ROMs....
Why put your hard-earned money in the pockets of someone who has had no original product to sell but sucks off the property of others (copyright).
No need to start another copyright flame-war. But answer this question: do you work for free?