I agree with most people on here. If I only need a couple things, I'll eat the $8 shipping cost, especially if it's something I simply cant find locally. However, If you're already buying somewhat of a bulk order, and are within 10 bucks of the free shipping, a couple good mainstays would be extra sediment/carbon filters for your RODI unit, or upgrades on size of carbon/GFO/dosing powders. If it were me, I'd just slap on another RODI sediment filter and carbon block and call it a day. Problem for me though, is that I order those from marinedepot because they carry 0.5 micron size and DFS doesnt. Just an idea