Reddit reviews TOGGLER SnapSkru Self-Drilling Drywall Anchor, Pack of 20

http://www.amazon.com/Coleman-Cable-3-Outlet-Extension-20-Feet/dp/B00004SQHS

http://www.amazon.com/TOGGLER-SnapSkru-Self-Drilling-Drywall-Anchor/dp/B0051IB63Q

There, solved your problems for less than $20.

The stand is tripodal so you simply need something that can withstand the weight at those three points.

wickedpissa mentioned bedrisers which is the right idea - support the stand at it's three points with minimal equipment - but could be a little low on substantiality (not a word but best describes what I mean).
Because the stand will be much bulkier than, say, a bed riser, it will be prone to knocking the riser over. Something with more mass such as concrete block would not be prone to such a problem and would give you about 6 inches of rise.

Your next issue to overcome is that the rising of the stand will place the center of mass at a greater height than what the stand is designed for. When too high, the stand is liable to fall over. This can be resolved by either A) attaching to the wall (as seen in many tall pieces of furniture) or B) attaching the stand to the risers.

What I would do is take three concrete blocks from your local block and brick supplier and cover them in carpet (for aesthetics). Next, just plop the stand on top. Then use concrete or drywall anchors to bolt a wire to your wall. Then attach that wire to a point near the top of your stand to keep it from tipping.

There are shelving styles, and anchors that will hold 18 pounds. these anchors, for example Would definitely be strong enough, and there is a video on the product page if you scroll down, That will show you how to install.

Drywall screws, despite the name, are not for drywall. At least, not in that way. They're to go through drywall into the stud behind it. So either you need to use some sort of drywall anchor or fasteners into the metal studs.

As for the weight, that's not really that big a deal, not with something that large and relatively light for it's size. These little guys have a listed sheer strength of 105 pounds on 3/8" drywall. The working load (for safety) is gonna be roughly 1/4 that, so let's just round down and say 25 pounds. That's only 2-3 of these anchors to hold up your art. So say you mount the french cleat using one every 8 inches, that's 6 anchors (if the 4 foot dimension is width), and there you go. The art itself will be hanging really close to the wall, so leverage is minimal. The load is static, so you won't get any extra force from movement. Hanging it on drywall will be fine. Hell, you could go seriously overkill and put in an anchor every 4 inches, if you wanted (though that may damage the integrity of the drywall if they're too close together).