Hey there,
I agree it's expensive but I try to look at it like this....
If I smoked or went out drinking every weekend - which I don't do but many people do- I would be out much more money than the money I pay for my session each week and it wouldn't help me half as much lol.
We often spend money on other things and dont realise how the costs can build up, or we happily give someone else money each week or spend money on others and dont realise the cost of it, which can be much more than therapy.

I don't think of it as self indulgent (which isn't a bad thing anyway) but as self care!