The amount asked for Bronze membership is $20.00 US. But if you think that's too much you can pay any amount, even as little as $5. You could probably get away with $1 but surely nobody is that cheap?
Bronze membership is really worth it because it allows you to use your own QSL design. Free members only get a plain text card which is pretty boring.
I'm glad eQSL allows free membership because it's better to have as many hams as possible registered with the system (and hopefully take the steps needed to become Authenticity Guaranteed) even if they don't pay a cent. According to eQSL nearly 90% of members never donate any money. I'm not very good at mental arithmetic but if every user paid something then the minimum membership fee would be about $2 a year I think.
It's always tempting to freeload, to put off donating until another day, but I think everyone should donate to help keep running the sites they use most.
Here's my list of sites I use most every day and would really miss:
Which ham radio sites would you really miss if they closed tomorrow?