Careful getting ur resin off eBay. I get my resin locally from a guy in Santa Ana and it's a little pricey. I started looking on eBay and found some good prices. The resin ended up lasting half as long as the more expensive stuff. U get what u pay for when it comes to resin.
And yes the refillable di is cheaper then buying cartridges.
I use BRS resin and I have no complaints. I've used both the color changing and non color changing and I stuck with the non color. It's nuclear grade (whatever that means) lol