I wouldn't be concerned about parts availability on the CZ. The Ruger will probably be easier to find parts for in 100 years, but the CZ is one of the most widely produced designs currently made. There are also tons of copy cats that use the same design with their name on the side. CZCustom.com is like the Performance Center for S&W, well sorta. They are run by great guys and they put out some quite amazing production pistols. They are rather popular with the CZ competition crowd. If you fear you won't be able to buy parts springs, I'd grab springs now on the cheap. I don't personally see parts supply being an issue, as they are made and used over seas by the thousands to tens of thousands. If CZ has issues in the US (which I don't see happening) replacements may become more expensive, but it really is the Glock of the EU/Asia from a volume standpoint.
I put an aftermarket hammer and sear as well as springs in my CZ and it is amazing how well the pistol responded. It's simply too well made to let go for the money they sell used. The GP100 is another great value too. Clearly on the revolver side of this forum people will tell you to grab the revolver. It's not a bad idea if you can't afford two and want the revolver more. I would caution that a GP100 isn't an overly expensive firearm so selling/trading one you enjoy to acquire it may be a regret rather than simply saving funds to buy it outright in the future. I'd personally rather save my pennies and cut out a little luxury spending to have both rather than lose one.