Run, don't walk, and buy it! Seriously, if you can buy only one plug-in for SR it's probably the one to get.You will probably get many responses from the list here extolling the virtues. It really is a great program and adds tremendous capability to SR.
I forgot something important. Boris FX by Artel Software http://www.borisfx.com/ is considered a "must have" plug in effects program by most everyone who has it including me. If you only buy one plug in package, it should be Boris FX. It has drivers to work with just about all NLE software including Premiere. You will probably not be able to equip every system, but it is very powerful and in wide use. It does 3D DVE effects that cost half a million $ not too many NAB's ago. All must render, but it does so remarkably fast. It has dozens and dozens of prebuilt effects which can be modified. Gets you up and using it with spectacular results right away - before you even really learn to program it. They have the new ver. 3.5 out now (does cool particle effects among many others) and if you buy now you will get ver. 4 for free when it comes in the fall, I believe. It will have a full 3D character generator included. List is about $500, but you can get it under $400 if you look for it. Price is supposed to make a big jump up when 4.0 is ready.
Also highly recommend you get your students into Photoshop and After Effects. I am a beginner on Photoshop and haven't cracked AE, but they are extremely widely used in all corners of the market today. Very marketable skills. I am sorely in need of getting up to speed on these. Digital Fusion from Eyeon Software is a worthy competitor for AE, I'm told, but AE has incredible market penetration.
Also, just read a forum message that informed that there is an article in the current New Media mag about RT NLE systems in general and in particular compares ReelTime/Premiere to DigiSuiteLE/Speed Razor. Might be interesting reading.