Ugh, when I hear or read things like "so far, so good," I cringe. Optimax nailed it - the savings of a cheap rack pale in comparison to your potential liability if it fails. Insurance
shouldn't be expected to cover such recklessness, IMO.
FYI, Planet Cyclery sells the Saris Bones 2 for $130, but they don't list its
weight capacity, they just say "two bikes." A visit to
Saris' website, however, says "2 bikes, 35 lbs each."
This doesn't mean you can put
one bike that weighs
up to 70 lbs on it and assume it's good to go. The straps that hold the bike on the rack are probably not designed to sustain that much force bouncing up & down when you hit potholes etc., and even if you duct tape or rope it down, the concentration of all that weight on one section of the rack might cause it to buckle, eventually.
I got the Saris Freedom Superclamp 2, which is rated for 60 lbs
per bike and lists at $430.* I also added two
Curt Stabilizer straps for $9 each - they really do stabilize and help support all that weight! I now drive with the utmost confidence that, in the highly unlikely scenario of my ebikes bouncing off at highway speeds, USAA will "have my back."
* My brother and I found our Superclamp racks from two different websites - 6 months apart - for about $350 shipped. If you search and/or can wait a bit, you can probably find one on sale (eTrailer and Outside Outfitters currently show $430). His Subaru Legacy came with a hitch, but my Honda Fit required another $200 for a hitch, installed. Well worth it!