Here is information on how to source each part. For reference I've included a picture of all the parts included in my kit.

2 Buckets and 1 lid

I've had the most success by far getting free buckets from bakeries. You can also get them at some bulk food places (things like peanut butter come in buckets), and also at sandwich places (pickles come in buckets). Be wary that pickle buckets will always smell at least a little bit like pickles.

Places I've gotten free buckets in San Francisco: http://growbucket.life/faq.html

Blackout material

The idea with blacking out the buckets is to reflect light on the inside of the buckets, and block light on the outside (unless you want your bucket to double as an intensely bright lamp).

If your bucket is white, then it is already reflective on the inside, and you just need to black out the outside. I've tried using black duct tape, paint, and stick on vinyl (you can see the comparison in my project diary). I haven't tried thick black paper (the kind students use for posters), but I think it would work and be cost effective as well.

If your bucket is colored, then you can make the inside reflective and block the light from leaving by lining it with mylar. My local TAP Plastics sells 2 ft wide mylar for a couple bucks per foot. You'll need 3 feet of 2 ft wide mylar.

USB Fan

Any caged USB fan will work fine (about $7 on Amazon). If you will be keeping your bucket in your bedroom or study, you may want to invest a little bit more in a quieter fan. I did a test and found the Stylepie Fun Fun Fan to be the quietest ($15 on Amazon and maybe a little cheaper on Aliexpress -- search 'summer fruit USB fan'). You can also solder together a computer fan solution (example tutorial).

Electronics from Amazon

These are the best prices I have found for parts available on Amazon.

USB power adaptor

You can use any USB power adaptor. My fan takes 0.5 Amperes of current, but don't worry if your USB adaptor says 1A or 2A on it. The fan will only draw the amount of current that it needs. I can find these for $4 at any local corner store or dollar store, and you can probably get them for about the same price on Amazon. If you have a spare USB adaptor for charging your phone, you can use that too.

Parts from local hardware store

2 three foot (or longer) extension cords ($3 each at my local hardware store)

8 hex bolts, 3/4 to 1 inch long, size 4-20 (9 cents each at my local hardware store)

8 nuts, size 4-20 (7 cents each at my local hardware store)

Polarized three outlet tap ($3 at my local hardware store) *make sure this doesn't have a ground prong if your timer doesn't accept a ground prong*

I include an extra 6 ft long extension cord with my kit, in case people want to have the bucket further away from their outlet.

A note about the tools

I have this lovely cheap Wen brand dremel that I got on Amazon for less than $30. It's served me well except the button that locks the bit when you change it came off once and I had to hot glue it back on.

I DO NOT recommend using the cutting disks that come with the Wen tool to cut the plastic buckets. They snap very easily. If you decide to take the risk anyways, you MUST wear safety glasses.

I recommend wearing safety glasses in any case -- I always get plastic dust in my eye if I forget to use safety glasses.

WHOLESALE PRICING

If you are making a whole lot of these things, I recommending sourcing some of the electronic parts from dollar store suppliers. I sourced my extension cords, lightbulbs, and polarized tap from dollar store suppliers. Here's an article I wrote about the suppliers I used. These suppliers are domestic to the USA.

I sourced my fans and USB power adaptors from AliExpress. If you are ordering a lot of something, it's worth messaging the seller for a bulk rate (and to make sure they actually have enough stock). Items that have free shipping on AliExpress are generally shipped via sea freight, and take about a month to arrive in the USA.

My lightbulb socket to power adaptors were sourced via Alibaba, by messaging sellers. For Alibaba you will have to pay shipping separately. I recommend FedEx or UPS shipping to get your order to you faster from China. Unless you have a shipping agent, stick with FedEx, UPS, or DHL. You can read about some of my learnings about shipping in my project diary.