From the research I have done , not all apples are apples. Most of the Kits have tonal variations dependant on what types of hardware tthey use to build them Mableaudio in China appears as the cheapest, but they use off the shelf modern parts and their amps lack that warm tonal sound that comes from a Classic JTM45. Going through the US based kits the better the components, the greater the costs.

Mableaudio prices range from$358USD to $408 USD for an assembled kit/No case.
there prices are similar for the 5F6A Bassman Tweed on wich the JTM45 is based.
The US kits and Ceiratone kits range in price upto more than $1000USD

The compartive kit types are

JTM45 - British 45Watt. 5F6A Tweed Bassman 40Watt
18 Watt British 18Watt 5E3 Deluxe Tweed 16Watt
5F1 Champ 5Watt

Depending on whether you want to build a Combo Unit or just a Head unit will determin which might be the better amp to build.

With a combo Unit the Bassman and Tweed deluxe represent a more compact unit to build
With a Head Unit the JTM45 offers a more open and manageable design. The issues with putting a JTM45 chassis into a combo unit relates to the fact that the chassis backpanel faces down and is awkward to access, while the Fender Units have the valves facing downwards, and the chassis design is more compact.

Overall the smaller the amps are in power the easier they are to build.

Be aware these amps when operating carry High Voltages that can kill the JTM45 valves operate in the range of around 690Volts.
If you don't have someone that can help set up the tube bios, then maybe get one that is already fully assembled.


Cheers PK