If you have decided to move forward I suggest going with a Solid State Relay system based around PID controllers. A company "Auber" produces one called the EZ-Boil. The EZ-Boil has the very nice (and unique) feature of not only having PID control but also having easy to access Duty Cycle control for boiling your wort.
https://www.auberins.com/index.php?main_page=product_info&cPath=53&products_id=560
Other PID controllers in this category like the Inkbird ITC-100RH do have duty cycle control but it is not nearly as easy to use as the Auber.
Make sure you use a GFCI (Ground Fault Circut Interrupter) for more safety. They can be had on Amazon for cheap and will save your life if something goes wrong. GFCI plugs will cut the power with a contactor to your element if the continuity between ground and common is broken. Instead of you being shocked and hurt the power will be shutoff.
Amazon Link to a GFCI rated for the correct Amperage. https://www.amazon.com/Leviton-16794-20-Amp-120-Volt-Right-Angle/dp/B00HRF31AC/ref=sr_1_4?crid=3G4AFGNJ0277U&keywords=gfci+plug&qid=1565642998&s=home-garden&sprefix=GFCI+pl%2Cgarden%2C140&sr=1-4
Bobby from BrewHardware in New Jersey stocks essentially all the stuff you need to build your own electric setup. I would also recommend these elements from Amazon, a buddy purchased them and they have been great. TC Element
If your buddy is a TIG welder and doesnt mind helping out you are in luck. TC ferrules can be attached to your kettle with hard-soldering and thats great but nothing will beat a TIG welded connection in terms of strength. If your buddy is not a TIG welder or doesnt have access to one it is very possible to solder on your connections with a solder formulated for bonding to stainless steel. Soldering on a TC ferrule
Links to Ferrules and Electric brewing parts on Brew Hardware https://www.brewhardware.com/product_p/ptbulkhead_tool15tc.htm
Goodluck! if you have any questions let me know.