As of June 1st, two new Lego Roller Coaster sets are available. One small, one large, with prices to match.
The first is the Creator Expert Roller Coaster (10261) which has 4124 pieces, and retails for £299 and $379 respectively. That makes it 7.3p/9.2c per piece. This is a gigantic, expensive, highly detailed set which will go very nicely with the Carousel and Ferris Wheel. I do think the price is quite high, no doubt due to the large amount of new track pieces involved, but definitely higher than the other fairground sets. I also think that for that price the power motor functions should be included, rather than you having to spend even more to have it run hands free.
There’s a designer video for this one…
If that’s too much for you, there’s also the Pirate Roller Coaster (31084). This is a much smaller, with just 923pcs, but it’s also priced lower at £69.99 or $89.99. This is a slightly more expensive 7.5p per piece, but your overall investment is smaller. This actually seems more creative to me than the big set, with the strong pirate theme, half ship on one corner and skull passthrough at the top. It uses the same track pieces as the larger coaster (and the Joker Manor from last year), which means you could technically combine them both together for an even bigger run.
As it’s also a 3-in-1 Creator set, you also get instructions to turn it into other fairground rides such as this one…
There’s no doubt that with the right budget, you could buy 3 copies of this set to have every model, the large Roller Coaster, the Ferris Wheel, the Carousel and the Friends theme park sets and have yourself quite the setup.