great thermometer because so many readings are affected by their temp
Acid testing setup, titration kit and the necessary glassware and reagents
PH meter with storage solution and preferably a model with replaceable nodes
SO2 testing method, titrets are okay to start. an Aeration/Oxidation setup is more advanced and by the time you get this far, you really should have a dedicated Lab area for your winemaking as the assortment of test stands, burets, flasks and assorted gear starts to add up.
a great book on more advanced winemaking techniques, alot of which involves the lab and chemistry stuff, like From Vines to Wines by Cox or The Way to Make Wine byWarrick
the refractometer i have i think i got on a special clearance deal from grapestompers.
model is RHB-32/ATC - basically 0-32% brix on 0.2%brix increments with an accuracy of +/- 0.20%
came with a little cordura carry case and plastic titretor and adjustment screwdriver and instructions. IIRC it was ~$50 refractometer i think i paid ~$25 on sale/clearance. maybe it wasn't grapestompers, could have been another online source. most of the online sources carry the same one i have for about $50 or so. no idea on the "brand" as there's no indication on either the device or the instructions.
looks like this.
as to Ph meters, i've heard good things about the Milwaulkee Ph51.. might be out of your price range tho, again ~$50. many of the less-expensive ones don't have replaceable electrodes so the good long-term play is to spend more and get one with replaceable electrodes.
Unless you will be making beer ag or growing your own fruits or buying grapes I dont think you need a refactometer. It is a very nice tool if you are doing any of those but for juice its not needed, PH mter would be te best thing to buy and 95% of the time you get what youpay for so dont get the cheapest thing out there, Id go Hanna. If I were to get a refratomter and I do absolutely need one with all my black curre]=ant bushes going and making ag beer Id make sure it was a ATC model! (Automatic Temp control)
I like Rawlus's list with the exception of the refractometer. I think all the converting that is required because of the ETOH distortion is just not worth it. I like using a hydrometer to monitor fermentation. I have only used the refractomer in the vineyard and I am now at the point where I just rely on the vineyard to supply me with fruit numbers.
I would buy a pH meter, A/O SO2 setup and a TA setup as the best tools to go 'to the next level'.
I am not endorsing...well I guess I am...but I like the benchtop pH meter I bought from Valley Vintner. It was $145.00 and it has been wonderfully. It is very consistent and maintains it's calibration.
I also bought my A/O & TA rigs from VV but in hindsight would probably piece it together myself from Nova-Tech International or some other scientific equipment supplier.
A good place to buy an accurate digital scale is at a head shop... I don't know if you guys have these down in the states since your drug laws are a little more severe than ours in Canada, but we have a lot of little stores that sell "smoking accessories," (eg. bongs, pipes, etc.) and they usually have decent little digital scales that read to the tenth of a gram. A decent one sells for about $75-80, but I find it's invaluable.