I had a few domains at Mydomain.com and they expired recently, I just logged into my account and clicked renew and just got charged the normal amount ($7.61 with coupon bargaincat.com). I know most other companies make you pay crazy amounts even just after one day so it was welcome to find that Mydomain.com still allow me to renew a few days after without extra fees.
Various registrars actually let you renew expired domain names at their normal prices. But you're correct that some will charge extra after expiry, especially if it's actually to redeem rather than renew the domain. As always, stay on top of your renewals and this sort of thing can be avoided completely.
yeah it's better to make sure they are renewed ealier anyway as some registers charge $80 or something to redeem them.
I have had to pay Godaddy large amounts of cash just after my domain expired 2 days later so yes it is good to see some registers don't try to profit from that.
Another reason as to why you should stay from Godaddy unless you really gotta use them. Best thing is to always keep on top of your expiries & renew well in advance.