Ouch! I'm just about to start shopping hard for one exactly like that - same size, clear glass. I've seen some made-to-order with 1/4" glass advertised on eBay for around $450 and thought that was kind of high. For that small size, 1/4" thick seems plenty sturdy. We've got 3/8" thick on a much larger door and panel downstairs ($850 installed?), and I just couldn't see anything that thick for a door that small. I'd suggest you keep shopping!

If you're talking about JUST a door, not a door plus stationary glass panel, it won't be that much. I think you can get the plain 28" wide door for about $250-$300. I have a couple of thoughts. One is: if you're going all out on a totally fab custom shower, make it bigger!!! The extra materials woon't add appreciably to the final cost at that level. I don't think. Two: there are a LOT of ways to economize and still have a very gorgeous custom-looking shower. Like: choose your drop-dead gorgeous tile for accent only... like in the niches or a border, and then use a less expensive field tile everywhere else. We used $2.25 tile for the walls but $35.00 tile for the shower floor and niches. And look into less expensive door options. Is your heart set on totally frameless glass? if not, semi-frameless is less expensive. Go ask at the special-order departments of Lowes/HomeDepot what glass doors they carry. Stock sizes, even in frameless, might be less than you think. And check eBay. We got our shower glass from a company that advertises there and it's perfectly nice. Same with plumbing fixtures. If you shop on line you can find things at nearly 50% less than the MSRP. I'd say downgrade your materials just a little bit, increase the size, and it'll still feel totally luxe.

We placed the glass at about the height that the shower head comes out of the wall (which is high as we are super tall folks). Our glass will be 80" above our 6" high curb. When the glass guy came to look (he came when I wasn't there, just with DH- that was worrisome!) he was looking at the top of the door trim, then the top of the recessed cabinets as possible guides- but when DH pointed out dutifully where I wanted it, and why, and where the deco trim was, and the grout lines... he said, Oh, yeah, that works too. But I thought those were all good ideas- it never even occurred to me to match my door trim to my medicine cabinet heights.... like I said, we're tall, the mirrors needed to be high so we could finally see our whole heads without bending our knees ;-)

Lol (I'm reading the comments thus far).. I did learn I have the u channel set up. Thanks John. Back to the org post, I'm no pro but my shower is about 46 inches wide. If you have a 42" opening then can't the installer do a set up similar to mine, but with a door that is a couple inches less in width? The door I have is the widest I could go, per the installer, so I don't see why you couldn't just do a door a couple inches less in width with the same fixed side??? By the way, my installer let me scroll thru pics on his phone of his past work. I saw all sizes with both u channels (aka the strip lol) and clamps.. My glass is 3/8" thick... Half inch cost more of course. I didn't even have him quote me half inch... Let us know what you find out