[ailideex]

I don't know exact details, but if it works like bitcoin miners can refuse to put renewals in blocks if the fees is not high enough.

[xur17]

In which case you can just wait until there are less transactions waiting to be confirmed, driving the price up (it's a renewal, so you have plenty of time to complete it).

[remram]

You can't wait to renew, or someone who's willing to pay the price will steal your domain.

[xur17]

I'm pretty sure you have a time period during which you can renew the domain.