I ordered the rest of my supplies from Seattle Fabrics. They have a great selection of outdoor fabrics and associated products.
Tent Fabric OptionsI ordered samples and considered five options for the tent material. These are listed in the order I ranked them.
Weather Max 65 I eventually chose a polyester product called Weather Max 65 in a charcoal color.
http://www.seattlefabrics.com/nylons.html#weathermax It comes on a 60" wide bolt and runs $14.50/yard. Here's their description: "100% solution dyed polyester incorporates UV resistant characteristics for long-term color and strength retention along with excellent breathablity and abrasion resistance. The HydroMAX finish raises the bar of hydrostatic performance and delivers unsurpassed water repellency, mildew and oil resistance without relying on environmentally unfriendly coating compounds. WeatherMAX 65 has anti-microbial properties and a minimum UV resistance of 1000 hours but only weighs 6.5 oz./sq. yard due to the use of a filament rather than a spun yarn like acrylic fabrics. Excellent for anything from horse blankets to tough outerwear to marine grade tarps."
1.9 oz FR and UV Coated RipstopRockywoods, in Loveland, CO also has a good selection of outdoor materials. They offer a UV and fire resistant coated ripstop.
http://www.rockywoods.com/Fabrics-Kits/All-Ripstop-Nylon-Fabrics/70D-coated-Ripstop-Nylon-Fabric-with-FR-and-UV-Treatment It comes on a 60" wide bolt and runs $9.59/yard. Here's their description: "This light 70 Denier (or 1.9oz/sq yd) ripstop nylon has 3/4oz of polyurethane coating to make it impervious to wind and water. It has been treated with a flame retardant and UV inhibitor. Flame retardant to pass ASTM6413D. The UV inhibitor makes this fabric suitable for longer term use out in the sunlight. It will still fade and weather over time but at a slower rate than our standard 1.9 oz ripstop fabrics. If you are looking for a permanent awning or covering, we'd still recommend using a Sunbrella, marine fabric or our exterior blind fabric as they are engineered to withstand the sun's UV rays." UV performance steered me away.
Super K-Kote Ripstop It comes on a 60" wide bolt and runs $11.50/yard. Here's their description: "4 oz. per sq yd. 140 Denier with 1.5 oz coating. This heavy weave of ripstop with an extra heavy urethane coating makes the fabric extremely waterproof and durable." The sample felt very sturdy, but nylon doesn't hold up as well over time to UV exposure.
1.9 oz Silicone Coated RipstopIt comes on a 60" wide bolt and runs $8.50/yard. Here's their description: "1.9 oz. sq yd before coating 70 Denier. The silicone coating is lighter than a polyurethane coating and the silicone coated ripstop has a 16-18 lb tear strength making it more tear resistant than the polyurethane coated ripstop. Uses include tent rain flies, light weight tarps, ponchos, pack covers, vapor barrier liners for sleeping bags, kites, wind socks." This is lighter in weight, less expensive, and yet durable. However, UV resistance steered me away.
Storage TarpsStorage tarps are available in various weights and are quite durable and inexpensive. If I were to build a galley tent on a tight budget, I would seriously consider buying tarps for raw material and using fiberglass tent poles instead of aluminum.
Miscellaneous ItemsThe remaining project items included zippers, webbing and grommet tools.
ZippersI'll use #10 coil zippers with double sliders for the six windows. These are purchased by the yard and cut to length by the user. The windows will be formed in an arc shape and the coil zipper will handle the curve better. I'll use an 84", #10, one-way, Vislon, marine-grade, separating zipper for the door.
WebbingOne-inch nylon webbing will hold the sleeve around the galley, provide stake-out points, and connect clips from the tent body to the frame.
Grommet ToolsHere's an area that's a bit of a "rub" for me. I needed to install 9/32" spur grommets to provide a solid attachment point for the tent frame legs to the tent body. These four grommets will cost me a total of $95 by the time I purchased the specialized tools...OUCH! Oh well, now I've got them.
The order from Seattle Fabrics cost $680 before shipping. This brings me to the "insane" total of about $1,000 counting special tool purchases!

We're looking at this galley tent as a "game-changer" since we do a lot of gourmet cooking in the galley no matter what the weather is doing. If it keeps us from upgrading to an Airstream down the road, this is money well spent!
I found out today that Seattle Fabrics only had 23 yards of the Weather Max 65 in stock out of the 33 yards that I ordered. This could mean I'll be taking a partially completed galley tent on our FL trip. I overbought, so it could be close...