If its a serious league then $20-30 per player entry should not be too much to ask for months of enjoyment. Hell, we do $30 each and it covers teh site fee (RT sports) and a kicking draft / poker party which includes all the eats and drinks you can handle, trophies etc.
RT Sports stays active and accessible year round and gives our group an open forum to stay in touch and BS about anything year round... Definately worth it!!
I also join a "free" yahoo league but its definately second fiddle and rarely do all the members even care....