Programmable weekly thermostat for underfloor heating

A colleague came up to me and asked for help to solvehim the task of controlling the heating of the house. The boiler is old, there are no remote adjustments as such, but there is a circulation pump. Turning on and off which is necessary to maintain the temperature in the house.
The first option that occurred to me was thermostats for underfloor heating. We look at what can be purchased in Moscow time:
long screenshot

These freaks cost a total of three thousand rubles, while their capabilities are very scanty
I’m wondering a little about their price what will happen if the same thermostat is executed on arduino:
1. Arduino Nano - $ 6
2. Screen IIC I2C 128X64 SSD1306 OLED - $ 7
3. Relays with opto-isolation - $ 2
4. USB charge to power the household - $ 5
We get about $ 20. The work, of course, is considered to be in liter equivalent for friends, and making a case with our laser machines is no problem.
But then I jerked to look for the readydevice, and today's hero of the review was found. For about the same $ 20 (at the time of purchase it was about 1200 rubles), a much richer device was obtained.
About Shipping, or What is Sellers Shipping Method

Box and its contents. The thermostat itself, an external temperature sensor (simple thermistor), two screws and an English manual.

Incomplete disassembly. The metal frame is mounted on the wall, the thermostat clicks on it, and is closed with a decorative panel on top. Unfortunately, it was not possible to completely disassemble - the latches that hold the case give the impression of a monolith, they can be disconnected without breaking them.
Before turning on
read the instructions

. It details the selection of modes,activation of constant illumination, calibration of temperature sensors, setting up separate hysteresis for sensors, calendar operation 5 + 2 and 6 + 1 and 7 days, and many other goodies.

Connection instructions are printed directly oncase. Everything is more than obvious. In order to reduce the chances of nakosyachit to a minimum, the terminals for connecting an external thermistor are rotated 90 degrees.

Turn on. Immediately we see the test of the LCD screen. Apparently, it is universal, because several characters in this thermostat are not involved.

Work mode. The temperature reads 2-3 times per second.

No backlight. The LCD screen is oriented correctly, so when you look at it perpendicular to the case, top or left / right, the contrast does not change and is maximum. Falls only when viewed from below.
The watch is non-volatile, after turning off the powerSettings and time do not go astray. I did not check the calendar, because it will not be used. The thermostat fulfills the set temperature and the hysteresis is correct; in case of operation, the sun lights up and the relay clicks.
Here is such a charming thermostat with a touchscreen can be purchased, even taking into account the increased course, for a penny. Everything that hangs in our stores surprises either with its wretchedness, as from the prehistoric world, or with its value. At this price in China, there is even no sense in collective farms.