Tapeworm RX source??

I'm not able to find tapeworm rx for cats locally so I need to order some somewhere. I found 3 tabs at Entirely Pets on-line for $10.99.......but, is there a less expensive way to tapeworm cats than that? :shrug: My cats don't have fleas (I check often) but they DO eat the mice and birds they catch out in the barnyard so I need to worm them around 3 times a year...and with 3 cats that can get pricy. Any ideas on what else to use or a cheaper source? Thanks so much!