Adding rails to factory Roof Rack for bikes

I was reading that the factory rack is not held on very well and then I
was looking at some of the roof rack bars that clamp to the factory
rack and noticed that some of them just hook over the factory rack and
clamp together. So theoretically you could clamp the bars so tight
that they rip the factory rack off of the roof?

I have a 1998 S-10 Blazer with a factory roof rack and I want to
upgrade it to cary 3 bikes now and then in a few years a 4th bike
(small child now). I would like to get a Yakima or a Thule but they
seem so expensive for ocassional use.

Does anyone else have a blazer with a roof rack that has added bars.

Yakima had lowriders, thule has a similar product. These appear to
clamp around the factory rack.

Pro-Line has one
http://www.a1-autoracks.com/proline-...crosspars.html
Does anyone have one of these?

Or should I not attach to the factory rack at all?

Anyother source suggestions? Or compelling reasons to get the Yakima
or Thule?

What bike holders do you reccommend? I do not have quick release
wheels so I do not want to take them off. Thule looks better than
Yakima in this respect. Any preferences? Any others?

Thanks

Mark