Your luck is better than mine on Toshiba... I have waited for parts from Toshiba (which doesn't even run its own parts department0 for as long as 11 weeks.
HP, of course is very quick, but not any cheaper than Dells...
We have had NO trouble getting Dell parts because there are so many of every model that the online market is flooded.
Sony remains a major problem... as they control parts availability religiously... We have six shops, and volume definitely helps with most brands, but not with Sony... or Apple MacIntosh... so we acquire those parts through establishments in their channels.
I once waited three months for an CPU assemble from Dell... Finally called their repair and parts center in the Philippines by phone... They sent it immediately... it was here in 8 days. The part was made in San Diego.
Parts from any manufacturer for a unit more than four years old is very difficult for any manufacturer except IBM/Lenovo, in our experience.
Now that Gateway is on the rocks, their parts are handled by a third party and are no longer easily obtained.
But for us, Toshiba is next to Sony in difficulty, partly because the components that fail are sometimes odd ones..
But becomming a larger problem by the month are parts made in China for products sold in the USA... they have major reliability and "almost but not quite fit" problems.
When the customer is paying the bill out of a thick wallet, I like Lenovo best and HP a close second.
But the Compaq parts people are the easiest to deal with, and really know their parts, so they have good suggestions.
We find parts issues complicated by the fact that all our shops are in Colorado, New Mexico and Arizona where things go bad because of the dry air, dust, and ozone problems.
Our biggest gripe is the fees that we have to pay to be on the parts supply system of some companies.
Most difficult to deal with: Apple.and Sony. Most difficult to fix: Asus, Acer, eMachines, or any machine used along a sea coast.. Best to deal with: HP, Compaq (separately from HP), and Lenovo
Worst machines... well that is for another chapter.