There are a number of PID units availible that are suitable for low-end espresso machines, like the readily available Saeco SIN006. This Espresso maker is also known as the Starbucks Barista, Saeco Via Venezia, and has the same internals as newer models such as the Saeco Aroma.

You will need:

A 120-220v PID. This will allow the PID to run off of AC power
A Solid State Relay with DC input voltage and AC load voltage.
A K-Type Thermocouple
Arctic Ceramique or similar thermal paste
Volt Meter
Drill
Phillips Screwdriver
Heat-resistant wire (Automotive stores or hobby shops will have this)
2 Spade Piggyback connectors
2 female and 2 male spade connectors
2 short, stainless steel small bolts and nuts
Mounting solution for PID (velcro)

Items 1-3 can often be found on Amazon or Ebay as a kit for as low as $30. Inkbird ITC-106VH is one I am using.

A few notes:

1. AUBER has a ready-made solution as well. This costs a bit more, but has instructions and a PID unit that is likely better calibrated for use with this machine. However, if you are like me and do not need a PID that costs double the cost of one of these machines, this is a good solution.

2. Steam operation is not affected. When installed in this manner, pushing the steam button bypasses the PID and causes the unit to heat up to steam temperature, which is still set by the steam thermostat. Steam on these units is less than desirable anyway, but if desired, this can also be controlled by either another PID, or, a single PID using ALARM functions and an external DC power source.

Step 1: Opening Your Unit

First, you will need to disassemble your SIN006. The iFixit teardown guide will explain how to tear down the unit: https://www.ifixit.com/Teardown/Starbucks+Barista+...
You will need to remove the stainless top and the Plastic piece that is under the "deck" that the pump and other parts are installed on.

Removing this plastic piece is important, as it will allow you to install the SSR later in the guide, easier.

Step 2: Decide Where to Mount Your SSR

The solid state relay can be mounted in a variety of places. In my case, I never use the top-mounted fill spout, so, I installed it right underneath on the deck with the rest of the parts.

I mounted with 2 short stainless steel bolts.

NOTE:

This will require you to remove or cut the spout so you can re-install the top of the SIN006.

Step 3: Thermostats

The goal, is to replace the Brew thermostats with the SSR/PID.

To do this, you will locate your brew thermostat. In most cases, this will be the rear thermostat. Using a Digital Multi-meter, you can measure AC current and find which one receives power when the steam button is pressed. This will tell you which is steam, and you will then know which is brew.

Step 4: Insert the SSR

Once you discover which is the brew thermostat, you will take it out of the loop, and insert the SSR instead.

To make this easier, I installed new insulated female spade connectors on the wires that used to connect to the Brew Thermostat, and male spade connectors to the wires that go back to the SSR. This would allow for removal of the PID from the loop, and going back to stock very easy.

In my case, I had more wires than needed in the shielded cable I was using for the project, so I used 2 wires for each side (you can see one side has red/black and the other white/green). In your case, you will likely just have 2 wires.

From the images, you will see how instead of relying on the brew thermostat to open and close the loop, turning the heating element on and off, you will now use the PID/SSR to do so.

Step 5: Power for the SSR and PID

To make this all work, you need power.

To make life easier, again, I used new spade connectors, along with a piggyback connector on the power switch.

These wires go back to the 4-conductor cable I was using to carry AC power to the PID, and DC power back from PID to the SSR.

Step 6: Remove Secondary Brew Thermostat/thermofuse

To install the brew thermostat, first remove the original Secondary Brew thermostat/overheat thermofuse. This one is a thermofuse that is clamped onto a metal clip next to the Brew and Steam thermostats.

Be careful not to bend this way too much, as it will break the fuse.

This was an important step I did not see mentioned in all my research. What I found, was that without removing this thermostat, the unit would not come up to temperature. It seems that this "thermofuse" works in conjunction with the other brew thermostat to achieve the proper temperature in normal non-PID situation.

However, this thermostat is also the overheat protection. If you run your boiler dry (bad no matter what), or your PID fails, you could end up burning out the element.

Step 7: Install PID Thermostat

Finally, you will install the PID thermostat instead.

First you will need to work the threaded nut off of the thermostat so you are left with the tip. You may need to use pliers to crimp the tip where the braided cable attaches, to allow the nut to slide off.

Second, you will place the tip under the clamp where the old brew thermostat/thermofuse was.

I used some arctic ceramique 2 thermal paste around the thermostat to conduct heat better. This is readily available on PC Building websites, Amazon, etc.

Step 8: Add PID.

Because PID's are different, I will show how I mounted my PID, but connections will vary unit to unit, so will form factor. I have also not included instructions. Many PIDs differ, and you will need to read the instruction manual to know how to set up the PID.

I drilled a hole in the right side of my unit, and attached the PID using velcro. In the future, I may mount better, but this has held up for several months.