Your picture isn't clear enough to see how it comes apart. If it were me and I really couldn't reach it, I'd get a 10' length of 1/2" PVC conduit; attach two 90 degree elbows to it to make a 180 degree turn, and duct tape the other end to your vacuum. You might have to extend the 180 with a few inches of straight conduit to get all the way down in there, but that's easy enough. Then you can suck the crap out of the fixture while standing safely on the floor. And the parts will cost less than $5:

1/2" conduit

1/2" elbow

P.S.: What do you intend to do when the bulb burns out? Maybe it's time to invest in a taller ladder.

There is such a thing as a motorized chandelier lift, which will let you lower the chandelier to floor level so you can work on it. It requires some clearance above the finished ceiling, maybe a foot or so, IIRC, so whether you could install one would depend on what's above.

I did a quick web search just now. The cheapest chandelier lift I saw was around $700 plus installation. You can buy a combination ladder (can be used on steps) that goes up to 11 feet for less than $200. If that's enough, I guess whether the lift is worth it depends on how much convenience is worth to you, and how you feel about climbing ladders.