Hey John,
Now I'm jealous as hell that you have a Z4, even though my Z2 still rocks.
For me, I'm all about DIY. You can achieve as good results from DIY over spending tons of money on a manufactured screen, but that is just me.
The Z4 has great contrast ratings, so a contrast enhancing screen is not needed. Also, the Z4 has respectable ratings in the lumens category, so I would be carefull on getting something with to much gain. I use a matte white PVC material, which is a 1.0 or slightly higher gain, and it works great for my Z2, even in economy lamp mode.
A screen that is a high contrast screen can sacrifice color vibrance, and a screen with high gain designed to give you more "pop" to the image, will not be as good in the black's category.
Even though my HT area is pretty much light controlled, there are still times that I have the blinds open during the day and my kid plays games with no problems. We also have the lights on in the other areas of the room many times to visit or play pool, and still watch HD material on the big screen. Again, this is using economy lamp mode and a 1.0 gain screen.
I guess if it was me, and I had the Z4, I would not worry to much about getting some fancy screen. Heck, just painting your wall with UPW (ultra pure white) flat paint will look awesome, which also has a gain of 1.0.
Other DIY alternatives which I highly recommend are go to Menards (or possibly Home Depot). In the aisle that has the paneling standing up, look for the 4ft x 8ft sheets of Parkland Durotherm-Lite Panels. These are used by many for a "just hang and enjoy" type screen. They are a PVC material that is light weigt, durable, washable, and work great for a screen. They are 5/16" thick and have a honey comb construction, similar to corrugated cardboard boxes.
Anyway, one side is smooth white with no texture, that is the side you would use. You would have to trim the material to get your 16:9 screensize, unless your talking about going the 2.35 screen route like me, which would require an anamorphic lens(thats another story).
For my current screen, I built a wood frame out of quality 1" x 3" oak boards from Menards. I then used corner bracing on all corners and the middle support piece. Next, I purchased some Professional Theater Screen material from Dazian Fabrics, they have been manufacturing theater screen material and curtains for ever. I stretched the material around the screen and attached with industrial velcro on the back side. Screen size is 51" x 120" and all done for about $100. I'll guarantee you, you won't see much difference if any compared to these $500-$1500 manufactured screens.
Some people use "BlackOut" cloth stretched around a screen. This is a product used in drapery lining to "BlackOut" the sun totally. The rubbery side works very well for a screen.
A cheep one coat paint solution as an alternative to UPW is Behr "Silverscreen". There is a long thread over on AVS in the DIY screen section with details.
Here is another method for about $100 described on projector central. However, not sure about using paper, but they say it works. Whatever you do, you want to eliminate as much light passing throught the material as possible.
http://www.projectorcentral.com/diy_screen.htmIf you really want to get crazy, you could build a "Light Fusion" screen. This involves using a mirror, or plexi mirror, and then painting a transparent paint formula over the top. Gives you a plasma like result, but does require a lot of patience and testing and practice to get it right.
Now I need to get back to work...
