You usually have to pay a joining fee and then a single climb is usually not that cheap.
Have not come accross a gym in France or Germany yet that asks for joining fees...
However, the point about single entries being more expensive is certainly a very valid one (usually around 10-12,- Euros). But the current exchange rate from US$ is working for you
Otherwise, a simple portable hangboard might do the job. And door frames as always as a last resort