Differences between RAM...

There is _probably_ not a significant difference. All three of those companies seems to guarantee that the memory works or it can be returned, the shortest period being 30 days. No one will tell you (oh, surely someone will) not to buy from Crucial which seems to guarantee forever.

I put 'medium' cost memory in a G5 iMac 20 and it worked fine and passed the usual tests done upon it.

Be sure to use the various companies 'configurator' process and keep a record of it. I'd vote for saving the $100.

 

I also bought from OWC rather than Crucial. Thank you for fulfilling the prophesy about Crucial! I had no idea they had variable pricing.

 

No, one site's cookie can't read another website's cookie, only their own, so Crucial wouldn't know if you had been at Porche (unless there was a banner advertiser common to both sites that maintained a history in its cookie which is why I deny all cookies to doubleclick and banner ad tracking services).

Possibly a Crucial cookie can store the referrer site URL if you linked to Crucial from another site.

More likely, Crucial relies on your own history browsing their site to create a buyer/price profile on you. What they potentially can know is: The machine type you are browsing with, the browser you are using, the general geographic area you are from (with varying accuracy) and any page or link within the Crucial site you have clicked on.

And that's all (including adjusting the price on the fly) presumably legal.

 

All three brands state compatibility with your AlBook 15" 1.25, which is good. The 1.25GHz is a "Finicky" model (that's a technical term to be used only by highly trained RAM professionals). More generic modules fail on these models (15" 1 GHz & 1.25 GHz, 17" 1 GHz and 1.33 GHz) than on any newer Al Powerbooks

Therefore I would recommend going with a Samsung module on this Powerbook. The Archmemory site shows a picture of a Samsung, but doesn't confirm it in the text - they would be a contender if you could be assured you would get a genuine Samsung module (not just Samsung chips on a third-party board design, known as Samsung on Third or Samsung/3rd).

The Upgradememory site shows a picture of an old-school TSOP chip based module instead of a more modern MBGA design, I would avoid this module on that basis.

Crucial.... Well they are charging $355 for a $220 module aren't they? so...

Your best buy in my biased opinion is the Data Memory Systems' Samsung original module for $205 here: http://www.datamem.com/viewcat.asp?C=1108

I have bought memory from this company for five years, so I know they are honest and they know their Macs.