The handle itself is just an adapter that allows to screw on any compatible tip. There's no electronic control or temperature probe.

I bought a single handle (spare part of a REGAD 200) in an art shop as well as an adjustable power supply 3-12V 5A on Banggood. 2Amps should be enough but I doubt that a cheap power supply rated at 2A will deliver that so I'm aiming higher hoping to get 2-3Amps out

The different tips can be bought of Etsy (https://www.etsy.com/listing/831373388/tips-for-single-and-double-electric) for the leather specific ones and any French art shop (https://www.vaissiere-peintures.fr/vaissiere-peintures-produit-381.fr.html) for the generic one (round tip, flat tip). I spotted some shops in the UK who are selling those tips as well. Keep in mind that Regad is a french manufacturer, hence the easiest availability and popularity in France.

The tips I could find on Etsy use a single heating element as a base and offer different tips which screws on it

I then simply replaced the power plug on the handle to fit the one of the power supply. Added a bit of paint and a leather wrap for style.

Here's a summary of the total cost for each part

The specific tips for leather craft carries the bulk of the cost but at 136$, we're far from the 300$ (without the tips) from the ready to use version