In Paris they tend to strike very, very often. I've been multiple times during a strike. Best thing I do is use the app
citymapper. It will take the strike into account and work out the best routes with all forms of transport including Uber, taxi, etc. It's invaluable and free. See how today it knows where the strikes are and what alternative methods you can take! It gives you easy to follow step by step guides and even breaks down the cost, time etc. It even tells you which platform and carriageo nce you get going.
This is public transport option one if you want to do it as cheap as possible. I think I'd happily subscribe to the pro version for one month to use the more advance option with strikes as you get mix mode transport that will mix even more modes from bikes, ride hails, trains metros etc.
But this below is the standard cheapest option.:
Are you sure the strike is on the RER line to the park, often the strikes happen on one track/line.
Also note that if the strike will effect transport home Disney will put warnings out over the park tannoy to alert visitors.
On a side note if you ever visit London you can use it to pay and cover your public transport costs. I hope in time with the Paris metro payment system being upgraded the same will apply soon!
