Shopping Links

I'm creating this big list of things I regularly buy and you can consider these recommendations. Just consider any comments. The prices linked may change so I am not providing pricing and you will have to search and compare to see if the price is still reasonable.

First let me cover Kits.
My favorite Arduino kit is the Sparkfun Inventors Kit because it has the best documentation. It is expensive and you can find other Arduino compatible kits that are much cheaper and have just as much stuff.

I do use the BoE-Bot with Arduino kits. They are also expensive however having a metal frame and not being over simplified has made them my recommended kit for lack of something better. Please let me know if you have a preferred robot kit.

General parts etc:
5mm copper tape - other sources have been foil tape this is a bit thicker
RGB Flashy LEDs 5mm (Not sure the seller, but this link is popular)
Thrifty White Tile Board
3 Volt 1 Amp power supply
2 x AA battery holders
Coin Cell Batteries CR2032 - Any other CR2032 should be fine since these are a commodity. I use these mainly for paper electronics projects, but also for the Bartholomew Robots.
flush cutters aka; wire snips / side snips. These seem to be nice quality.
NPN transistors A really common type of transistor.
500 LEDs 100 each of 5 different colors
Leonardo Arduino compatible boards
50mm copper tape (to use with vinyl cutters)
Jumper wires M / M
red / black jumper wires. We tend to use more power and ground wires in circuits and this was the only place I could find reasonably priced for single colors. These have fewer strands than those listed above, but they are tougher and don't break easily. Just be more conscientious about how much current you put through them.

Tools:
Cardboard knife that kids can't easily cut themselves with

Stamp making supplies
No odor laser rubber for engraving stamps
1/8th inch rubber foam mounting for stamps
Ink pads

BTF Lighting has been good for LED strips and power supplies. This is also a commodity so if you have another preferred source go for it and you can let me know as well. I've liked what BTF Lighting has sent me so far.
store link
RGB LED Light strips. I like the WS2812B
Power supplies

These parts are for the Flashy signs I make. To cut the white board (thrifty white tile board) I use the laser cutter, but a cnc mill or shop bot should be able to do the job.
5mm copper tape
RGB Flashy LEDs 5mm (Not sure the seller, but this link is popular)
Thrifty White Tile Board
3 Volt 1 Amp power supply
2 x AA battery holders

Nebula Light Boxes
What I currently use to make Nebula boxes;
2 Mil Mylar 100 ft roll.
Clear Plastic Film Polyethylene
Keep in mind both of these are for greenhouses and one roll will last a long time. You may look for smaller rolls.
Ready Board foam board from Dollar Tree which is safe to cut on the laser at HeatSync Labs. Other brands are not because we don't have the Safety Data Sheet.
Alternatives to the above.
Mylar balloons - Not likely to work as unless you find some that are shinier on the inside than I found
Cling wrap - works great for light getting through, but annoyingly sticks to itself
Cardboard or literally anything stiff

Bartholomew project parts (listed and linked above)
50mm copper tape
NPN transistors
thrifty white tile board
CR2032 batteries