How close to Kortrijk / Courtray can you get with a Lille public transport ticket (and still make it there)?

A few people have mentioned to me that the Belgian town of Kortrijk / Courtray is nice to visit as a day trip from Lille, and with a good eye can apparently (almost?) be seen from the clock tower of the Lille town hall! (It's only 15 miles)

The WikiVoyage page for the city suggests that you can get a train there pretty easily from Lille, which given the short distance one would hope was the case anyway! However, the train looks to be a whopping €8.20 one way...

Given that a Transpole single journey ticket is only €1.50, and given how close Kortrijk / Courtray is to the border, I'm wondering if there's a cheaper way to get there relying more on local public transport? Say, perhaps, a Lille tram or Metro most of the way, Transpole bus across the border (still on the same ticket), then a Belgian bus the last bit?

Note that I'm probably not after the closest to Kortrijk I can get on a Transpole ticket, rather the closest where there's onward public transport. Well, assuming I can't use a Transpole ticket the whole way that is!