Options are pretty limited.
1. Renaultsport, which is probably the one you're thinking of that most people have.
2. "Jase" splitter
3. Maxton Design
4. RDX Race Design
And that's about it.
You can also fit the splitter from the Golf GTI Edition 30 and it lines up almost perfect and looks amazing if you ask me. There are probably a few others that can be made to work too. I know people have fitter Seat and Ford splitters to Clios.
If you just want the cheapest one, go for Maxton, but none of them are expensive by any stretch, so save a few pennies for a better one would be my advice. The Maxton stuff is very cheaply made. Splitters are usually WAY more expensive than these.