Marine depot doesn't offer refills but the whole kit is so cheap from them that may be way to go for many. I ordered a refill from Miller Analytical , thanks for the help. Here's my research for future cheapies:
Marine depot $20 for whole kit 4491-DR/ LM1111 with shipping within CA of $7 comes to 26.98.
BenMeadows 16.90 for refill and $28.94 with shipping from WI to CA.
Aquatic Eco $12.18 for refill plus $5 for being under minimum order amount of $20, plus shipping at about $11 so $28 final I think.
Miller Analytical does have a great selection of refills, you can get whole refill kit or just individual bottles. Prices: $12.20 for whole refill, or Ask for T2311H for the indicator pellets only at $5.25 for 50 or T2311J for a bottle of 100/ 7.25. Also available in bottles of 500 or 1000. These are drop shipped direct from La Motte. Estimating $11 for shipping from PA to CA looks like $18.25 for a bottle of 100 tablets.