This before anything else:
1. Fermentation chamber. I've attached a pic below showing mine (one large, one small). It's almost a given that, when asked what made the greatest improvement in their homebrew, experienced brewers will say "Fermentation temperature control."
The small refrigerator in the pic is a 4.4 cu ft dormstyle refrigerator. You can find them on Craigslist here and there for in the $50-60 range. A larger refrigerator will allow for two fermenters. If you do this, take along a fermenter to ensure it will fit, or that you can remove plastic door molding to allow it to do so.
Cost? Varies.
1a. Inkbird 308 temp controller. Allows you to control both cooling and heating in a ferm chamber. I have 5 of them. About $35, though the Inkbird sponsor on this forum regularly runs 20-percent off deals on Amazon, so it ends up being $30.
1b. You'd also want some sort of heat source for your fermenters. I've used both reptile heat mats and fermwraps on mine, both are fine though the fermwrap has more capacity (40 watts versus 21 for the reptile mat). Cost is from $16-30.
2. Jaded Hydra immersion chiller. When the groundwater is cold, I can take a 5.5 gallon kettle of boiling wort from boiling to 70 degrees in 4 minutes.
It's a beast. About $175 with shipping. Yeah, it's worth it.
3. Thermoworks Mk IV Thermopen. Very fast response, display rotates--I use this for mash temps, getting pH samples down to room temp, checking boiled water that's cooled for a dry yeast rehydration. They have a new one which also includes IR, but it's new and until it's shown to be excellent...
IR sounds like a great way to check a mash, but you're only checking at that point--plus IR is not always accurate depending on surface reflectivity.
About $99 for a Thermopen MkIV, but you can get them with a 20-percent off deal from time to time.
4. FastRack bottle storage/draining system. It's how I store my bottles after cleaning. They can drain down into the tray, no problem. It takes up far less room than a bottle tree, and one thing I really like about it is I can put an entire rack of 24 bottles in the freezer to cool them down prior to bottling. About $35
5. pH meter. CHeck the pH in the mash. Also significant in the quality of the resulting beer. I use the Milwaukee MW102. About $130. Also pricey, but it will move you out of the guessing mode to the knowing mode.
Your $400-500 budget is enough to move you into another realm of brewing. If you can, see if you can supplement it with some of your own cash as well. If you don't have fermentation temp control, that should be first on your list. The Hydra is a want, not a need necessarily, but impressive. I'd say the Thermopen is a need; fast and accurate temp monitoring is important. The Fastrack is a want; the pH meter is a need, IMO, since you're doing all-grain.
Other things like a finish hydrometer, digital scale (which you'll want if you're modifying water to pH), a refractometer--these are all worth getting before the big things if you don't already have them.
Good luck!
