I'll sell you my space saver if you want it. No idea how much. I'm happy to wrap it up and post it if you want - reply to the thread or PM me if you want it.
Mine's surplus as I got a full size 18" wheel as soon as I got the car. I don't fancy doing 50mph on a motorway on a pram wheel.
The 18" fits into the well, but I had to put about an inch of wood/rubber packing around it to raise the boot floor slightly. It still fits in though. The 17" should fit better, 16" better still, as I think they also get narrower with smaller diameter.
My full size one came from ebay, and is from a Vauxhall Astra. It has exactly the same dimensions and offset as the Croma, but obviously looks a bit different (but it's actually pretty similar looking).
I suppose at least a space saver is better than just the can of squirty goo you get with a lot of new cars. This was once just the case with little sporty cars, but a lot of mainstream cars have it now, especially 7-seaters (as they use the spare space for the rear seat legroom).
I'm amazed that there are no regulations requiring a full size spare, or even a spare at all.
The handling seemed to improve with a full-size spare too. A bit of weight on the back axle can be useful. Clarkson on Top Gear on Sunday had an old BMW with a paving slab in the boot. Skoda now put 25kg of "ballast" in the boot of the sporty Fabia.