As you will fall in it, as some point in time, I advice you to go to chamonix and try every brand ( and hang in it in the shop ) to get a perfect fit.

Don't worry about price. Convenience is more important. As Julian says you can get it in most good sports shops, whether ochsner or other. Rent equipment and see which system you prefer and once you find the right system buy it. You're speaking about your safety here. 

Some y combinators are long so more tiring to use. Some harnesses are for wider people. Take the time to make sure it fits. 

As a side note I use my via ferrata kit almost every weekend in summer. I have easily amortised the cost of the set through a year of frequent use. I have two spares which I can lend to people when they come to ferrata I organise. I even provide for those organised by others in some cases, this weekend being an example. 

For the Y part of the Via Ferrata kit, I strongly recommend the Mammut Step Brenta for two reasons.

First, the elastic cords are shorter than the typical "rope" model. This means you are not always fishing behind you to untangle it from the steps when you need to unclip and move to the next portion of the wire safety line. Second, the quick-locking carabiners are the best on the market. Very easy to open and close for the transfers. You will easily save 50% of the time and effort.

The Step Brenta comes in two versions. This photo link shows the one with the turning thing in the middle that keeps everything flat. The basic model is CHF 160 and the turning one is CHF 180. Both are available in any good climbing shop (even Ochsner). Both are cheaper from FR/DE is you have the time to go or order via Internet.

http://www.arts-outdoors.de/Shop/images/product_images/popup_images/4689_0_Tec_Step_Brenta_Turn_basalt.jpg

@RichardM

You could have a look at the Ochsner outlet in Aubonne (near Ikea) since you are near there. If no,t you could go to Leman Centre to the Ochsner store there. There are also the two upper end sports stores in Lausanne - Passe Montagne and Yosimite.

Remember as well that you need a climbing helmet (not a bike helmet) and gloves (bike gloves are good) tend to save your hands.

A useful site for shopping for sports gear in France is:

http://www.auvieuxcampeur.fr

I bought my via-ferrata, mountaineering and canyoning equipment from their shop in Thonon-les-Bains and the prices are interesting.  They have an on-line shop too, but I have not used it so cannot vouch for it.

I would recommend a climbing shop rather than internet so that you can try it out.  France is cheaper at the moment because of the weak Euro. but do not forget that if youare a CAS member or member of any other alpine club, you can usually get a 10 per cent discount in CH

I think you can also hire with option to buy, like skis 

One poster mentions that you will fall. That is not the purpose of via ferrata and a fall can hurt, especially if you fall just before a change over, despite the shock absorbers.

Verbier gives a detailed analysis of a certain system and I would tend to follow his advise or at least use it as abasis for discussion in the climbing shop.  Megastores tend to have a shortage of qualified people 

If you head into Geneva, the climbing shop in Carouge has a 25% sale on all items right now to make up for the 'Strong Franc' to keep people from going to France.

Just noticed that this weekend walking by.

Decathlon has a decent selection of harnesses and they are not that expensive.  They have Petzl and I think Black Diamond brands.....

Yes, I also recommend Decathlon, their own brand stuff is very good value and they also carry well-known brands. Intersport (there's one in St Genis) is also a good option, and they give 10% off for club alpin members. Both of these were much better value than anywhere in Switzerland even before the latest exchange-rate shift.

You don't need to spend loads of money. In my opinion you can get a decent harness for 50 euros, and the via ferrata Y-thingy for less than 100.

All climbing kit sold in europe passes stringent safety tests. If you buy a more expensive model it will probably be lighter, comfier, easier to use and more fashinable, but it won't be safer.

Thanks for everyone's help.  I'm going to Chamonix on Saturday.  It seems like the best way to chat with experts and try different equipment.

Also, I'm thinking about going to Vitam Parc later this year when the weather turns to crap.  What do I need beyond climbing shoes and a harness?  My own rope?  Quickdraws?  Yes, I'll sign up for classes first, but I want this shopping trip to be productive. 

For VitamParc you don't need anything else, even if you've got your own rope they prefer you to use theirs.

If you're aiming to climb outdoors then you'll be wanting a helmet, a rope (a 60m single rope is good for starters) and 8-12 quickdraws. But of course you'll also need someone to climb with and they might have some of that.