I was bored today so I did a quick comparison of 5 online stores with just 4 items and it was Lambert by a landslide. You may find cost for individual items at better prices from other stores but since most medications expire after 1-2 yrs it is more cost efficient to do all of your shopping at once for the entire year!

Fish Flex 500mg 100ct
Fish Mox 250mg 100ct
Pyrantel 32oz
Ivermectin 50ml

Lambert $108.30 (free shipping on orders > $100) called customer service to confirm shipping cost
Allivet $125.96 (free shipping on orders > $100)
KV $145.88 (free shipping on orders > $100)
Jeffers $137.80 (free shipping on orders > $100)
Revival $139.95 ($129.95+$10 shipping)