Yes, it is. You can get a 12-pack of tubes for about $170 or a bucket for about $155 I think. It works *very* well for its intended purpose.
Personally, since this is a rental, I'd think TWICE about doing anything that requires fastening HEAVY things to the ceiling. Frankly, you don't have a clue about the EXISTING CONSTRUCTION. And neither do I. However, unless you find out some info on how this room is built, you are at risk. Not only that, but just adding mass to an existing structure may not even solve the problem.
Let me put it this way. Many older multi-family buildings use HVAC systems that are COMMON to other suites/apartments. This is a perfect FLANKING PATH that can negate ANY solution you try. Furthermore, to overcome Low frequency vibration in the building structural assemblies, such as a wood floor membrane, will simply transmit to other areas. Especially in OLDER wood constructions. Newer, concrete partitions, floors and walls are another animal entirely. However, without knowing EXACTLY what you are dealing with here, I submit you are spittin in the wind speculating and gambling the solutions previously advised will work.
As to the Green Glue...take a look here...
http://www.soundproofingcompany.com/library/green_glue_testing/
Look at the rows of data. You will see a SOURCE side, and a RECIEVE side. What this means is unless you know what the SHEITHING or assembly is on both sides, you can't even guess at the STC improvement. Not only that, but for the cost of GREENGLUE, unless you are COMPLETELY sheithing the ENTIRE room, compared to the cost of drywall, the improved transmission loss may not even justify the expense.
I mean, for 12 tubes, at TWO TUBES PER DOUBLE SHEET of drywall, thats an area equivelent to 6 sheets of 4'x8'..or 192 sq. ft. Thats only a ceiling for a room approx 14'x14'. If one layer of drywall is say $8 per sheet, thats only $48 per layer for the drywall..or $96 for TWO layers. As you can see, the Greenglue is 1 1/2 times the cost of the drywall. And for what...a db or two improvement over just 2 layers of drywall, since you can't add Greenglue or drywall to the RECIEVE side.
Yes, Greenglue definetely improves STC and makes the two layers act as one(coincidence dip alteration...don't ask me to explain
). However, unless you can address ALL WEAK LINKS...I submit you are wasting money and time.
That is unless you have deep pockets in the first place.
And given possible existing flanking paths, wood membrane floors and ceilings(vs concrete), well, I hope you get my drift. Ok, thats my .02 I'll shut up now.
fitZ