Where should I get these items for 3 I2C sensors?

I need some help in finding a place to buy some pull-up resisters or some decoupling capacitor

Try the usual suspects: eBay, Aliexpress, Mouser, Digikey, RS Components, Element14, Taobao, Amazon, ...

umm… anywhere?

Radioshack
eBay
Digikey
Mouser
Element 14

Where are you located?

Also… might be able to use the internal pull-up resistor in each Arduino pin?

xl97:
Also.. might be able to use the internal pull-up resistor in each Arduino pin?

Often works but out of the specifications of I2C, and asking for problems if you connect three sensors to the bus. Likely to have too high a total bus capacitance.

Now if OP has breakout boards for those sensors (likely) they won't need decoupling caps or pull-up resistors for the I2C part as those are normally in place on those boards.

Forfeitguy1:
I need some help in finding a place to buy some pull-up resisters or some decoupling capacitor

There is a Radiospares about 8km from where I live, they stock most stuff like that.

IS the adafruit proto shield a decoupling capacitor?

No. Buy one of their kits that includes ten or twenty 0.1uF caps.

So what you're saying is that 0.1uF caps are decoupling capacitors.
If I'm wrong, I'm new to Arduino.

.....the prevention of undesired energy transfer between electrical media