I've got an ABS bag that I bought at Sport Schek in Munich about two years ago. Just happened that they had a sale on the bag, 20% or so. I can't recall exactly how much it was, but it ran about 450-500 EUR...
When you buy it, you are showed how to activate the balloons, refit a new canister and repack the balloons. This is done at the store and the guy was extremely helpful.
The bag is a little bit larger so I can fit a few things in there, like:
2 Sonders (graphite probes)
a camelpack (water)
an off-piste guide book of St. Anton
a hat, gloves, etc
a shovel handle
On the outside, there are straps that I fix the shovel to. I would get an aluminum one as the plastic ones could crack it you wipe out. Also, I would prefer to keep the shovel IN the pack as well, but it is held very fest on the outside. Reason being, if you get into an avalanche, all of this shit will be ripped off your body anyways. The pack has two straps which will hold it to your body - important when you deploy your balloons.
http://www.abssystem.com/A 15 liter-sized bag should be big enough to carry the things I mentioned - it's what I got.
Regarding the beeper, make sure you get a beeper like the one here (with the straps) - same reason as the bag - it could get ripped from your body.

However, I would NOT recommend getting an analog beeper. They're old, no one has them anymore. I know that a Swedish guy died last year on St. Anton because he had an analog beeper - no one could find him. Spend the extra cash. Also, the newer ones allow for multiple seeking. Mammut brand supports this functionality as well as others. But I would just get the most popular brand as it helps ease cross-training when traveling in groups.
When an avalanche happens, one person is supposed to search for the buried people. He can do this quickly, further finding the location of the body with the probe. He leaves the probe there as a marker for others to start digging here (assuming others arrive). With a newer model digital beeper, you can mark this location (buried person's beeper to be exact) as "found" and then move onto the next signal (other poor sole trapped in the snow).
All that having been said. I've seen an avalanche before and one of my friend's was killed in it. I watched the whole thing go down, it killed him and 3 other Canadians that day. I stood from above and watched it like a movie. I was the second one on the scene along with an Austrian guy. We pulled out a Canadian guy from 6 feet of snow, he lived. We then found his wife and 2 others in their party who died as well. I gave the Canadian woman CPR for 40 minutes while helicopters arrived. The beepers only helped to find dead people.
The moral of the story is, if you don't have an ABS bag on, but a beeper, your dead body will be found. Without an beeper, your body will be found in May with the snowmelt. And if you don't have a probe and shovel, you have no business being off-piste whatsoever. I saw people digging with their hands. Not really useful with some people buried 8 feet in the snow...
I’m glad to hear that you’re doing the course and show a need for such equipment. There are far too many people out there who think that this kind of a thing can’t happen to them. Also, I would not worry too much about the cost. It’s not only your life, but others as well. And unless you have all of the equipment that I mentioned, then you cannot save anyone. And they can’t save you.