What should I get next

So my parents sent me a $100 gift certificate to northernbrewer.com for my birthday, and I'm trying to decide what to use it on. Here's what I have already.
-Igloo cooler HLT and MLT
-Keggle BK with the normal fittings
-STC-1000 ferm chamber
-15g conical and a bunch of Better Bottles
-Kegerator and an ample supply of corny kegs
-Blichmann beer gun


I also have an arduino that I'll eventually be using to power the heating side of the ferm chamber.

So I've been looking at a few different things and here are my ideas.
-pH meter
-Refractometer
-Carboy washer
-Another boil kettle. (I could turn my keggle into an HLT and start my HERMS build...)
-Pump (again for the HERMS build)
-Heater blankets for fermenters.

These aren't the only options, just an idea of where I'm going. Let me know what my next upgrade should be!

Do you have an immersion chiller, plate chiller, or counterflow chiller? You may have just forgotten to list it, but that's the most glaring omission from the list above that I see. If you are headed towards a HERMS build, I'd get a 40 plate chiller.

Yup, a plate chiller with a pump would be a nice addition to that bunch.

Forgot to add that. I have an immersion chiller with a prechiller coil for the water, but I think I'd like a counterflow chiller. Northern brewer just doesnt have a lot of options on their website for CFC's and I only have around $100 to spend

Boil kettle or pump!