Maybe you could clarify this but I get the feeling that some of the posters are overlooking the realities of your area, where finding some scrap metal, chains, sprockets, and maybe even old motors are one thing but shipping in new or even used previously built tractors are an order of magnitude more difficult and not cost effective. Cheap labor means anything that can be built on site is going to be a better choice.
Well, the situation is nuanced. Kinshasa is (perhaps) Africa's second biggest city, with an estimated 10 million inhabitants.
If you search well, you will find almost anything, including perhaps a walk-behind tractor and a new, imported, highly expensive electric motor. But this requires a real search, and there are few channels in which you can work. You mostly depend on luck.
There are no real dealers of quality products, except for a few houses like Iveco and Yamaha. And even they have very limited stocks and choice of products. What is more, their price is consistently much higher than if you were to buy in the U.S. or E.U.
This is due to excessive taxes (on imports) and Congo's problematic logistics.
In short, we're touching one of the key reasons as to why the country is in a bad fix, and develops so slowly.
On the other hand, Kinshasa is a gold-mine for the so-called "récup" - that is all kinds of used goods that can be found, repaired, refurbished, adapted, what have you. There are literally tens of thousands of people in the informal economy who depend on this sector.
It's here that we're looking into finding the materials for our little experiment.
But then suddenly, when it comes to, for example steel products and the skills needed to manufacture something - there is no problem. Most basic steel products are to be found new (or, again, recup): tubes, plates, bars, t-frames, etc... Welding and metal workshops are plenty.
In short, as a starter, I could say that it's best to source everything locally. Importing is simply out of the question - unless you can rely on a person who can bring the object in his luggage from Europe or the US to Kinshasa. Else, importing is simply a losing proposition.
Let's not dramatise the situation: there are people here who succeed in building huge boats (barges) with very powerful engines and everything that this requires. It's doable, but you need some creatives and people who can search stuff for you. In this sense, the e-tractor is not a big project; in fact, I don't see any problem in finding the necessary materials.
On a final note: electric components should be kept to a minimum (not too many controllers, etc). But I can buy them here (EU) and take them with me in my luggage. But all the other materials: sourced locally.