well i finally purchased a custom 2.35:1 lenticular fixed frame screen (145" diag), it was shipped 4 business days after i made payment, it's en route now, so it will be interesting to see how long it actually takes to arrive.
my experience: there were no less than 10 different manufacturers on alibaba that carried what i was looking for (a lenticular / pet crystal fixed frame tension screen with thin aluminum bezel), and if not identical to one another they were awfully close... i also found that 120" (diag) was the max size for about half of the companies i contacted.
for me the easiest approach was to 1) within alibaba, search for pet crystal, lenticular, alr, etc. projector screen and then 2) send the same note to each company (contact seller button) detailing exactly what i was looking for (size, fabric, fixed frame, etc.), ask if they had it and, if so, what the cost would be including shipping to my zip code... i also attached an image of the lenticular screen graphic to the note.
from there it was just a matter of dealing with each seller via alibaba's excellent message center, and every single seller i contacted replied.
the quotes were all over the place, they varied quite a bit, while one of the forum's (seemingly) favorite dealers was considerably higher than the rest, not only higher but ridiculously priced if you required a size they didn't list, whereas the other manufacturers added a very reasonable (imo) premium for a custom size.
not only did screen prices vary considerably between suppliers, but so did shipping costs, a couple of companies said that on top of the shipping costs i would have to pay an import tax upon arrival and pick up the screen at the port of delivery (it couldn't be shipped to my location). several companies also told there would be an additional bank transaction fee for change in currency processing, and that would be required to be paid by me.
when i responded that i had recently purchased a projector directly from china and that i did not have to do any of this (pay an import tax, pick up the package at the port, pay a bank transaction fee, etc., etc.), all but one company said they had made a mistake, that no additional costs would apply, and that the item would indeed be shipped to my location.
so you get the picture.
also, fwiw, i noticed that a few of the companies i contacted tried to get me to move the conversation from alibaba's message center to private email or skype, and pay outside of alibaba... these requests could have been benign, but i couldn't help feel that they were trying to circumvent alibaba's transaction commission as well as alibaba's buyer protection which no doubt depends on buyer/seller communication.
bottom line is, when called on everything, additional costs, communicating outside of alibaba, etc., all but one company stepped up and was more than willing to work within what i considered to be the rules.
anyway, most of the sellers i dealt with were very nice, and i feel very good about the transaction, and the price... of course the proof is in the pudding, we''ll see if i change my mind once the screen arrives!