Don't mean to be funny, but £2.50 (£15 / 6) for a quality ratchet strap seems cheap to me. If Bill uses them for MotoMorocco he must reckon they're up to the job, but I'm a paid up member of the "You don't get anything for nothing" gang.
The one that bent cost me £10 IIRC.
I use a minimum of four on each bike Taff.....two pulling forwards, two backwards and another to whichever floor anchor seems appropriate if I've got any doubts whatsover.
I bin them if I've got any doubts about the ratchet mechanism and shorten the webbing strap to above any frays as soon as one crops up (which they inevitably will)
Initially I wasn't using anything to keep the hooks in the anchor loops- I chock down the suspension so it's solid but not compressed more than an inch or two, but even then I had one bike jump far enough over a big bump that a hook jumped out, so I started using heavy duty cable ties to anchor the loops (they don't actually take any force, all they have to do is keep the hooks in position if the webbing goes to slack over a serious bump)
At some point last year someone here offered up a load of crabs for sale, which David Hale and I split..they're easier to use than getting down inbetween three tightly packed bikes to get a cable tie on, plus they're inifinitely re-useable. (and have other uses too)
The Costco ones are a pretty good compromise in price and quality- be a bit careful 'cos they have offered a few types over the last few years, but a lot they do have had rubber coated release handles which is really nice, and inch and-a-half webbing straps rather than the rather weedy inch ones (I do have a load of these but prefer the wider ones)
I tie 6-7 bikes down at a time, so 28 ratchet straps + half a dozen replacements a year is an expensive proposition
I do rather like the look of these fancy self-retracting ones but at that price ?
I'd also want to run a couple for a while...I'd be concerned about crap reeling back in with the webbing and jamming the mechanism and long-term durability.
A can of WD40 and regular inspection is essential with ratchet straps, but as long as you look after them (and get Lizzy Whatton to go on the trailer with her OCD to neatly coil them all up occasionally
) then the Costco ones are fit for purpose IMO .
EDIT
PS I've also got a wireless camera in the trailer that shows me whats going on on an LCD screen in the cab, so I monitor the bike's positions carefully en-route as well......maybe a little OTT but it works for me
If you're towing your pride and joy behind the car, one of those isn't a bad idea either....about £80 all in
PPS Tarka, yes I know it's an offence to have a screen that....Oh never mind
I did manage to get a price from the UPS website, which was about $250 
- I guess either they or I had made a mistake. 
