What budget for this solar bike?

At the time of my registration at SunTrip, I had about 6 months to build and experiment my prototype, which limited the search for partners, and therefore the budget too. I obviously watched the presentation how to turn an electric bike into a solar bike by Bernard Cauquil. I admired his selection of technological solutions. Surely he had hoisted the bar very high. But the cost price of his machine was quite a deterrent to me. Besides, I like the DIY (= do it yourself), I like to be self-sufficient. So, when it was possible, I rather opted for the cheapest solutions, although I knew beforehand that they were not the best. This allowed me to have a vehicle for a reasonable price. The diagram below reflects the cost of the solar bike (out of partnership), it does not take into account the R&D budget that I have difficulty evaluating. The total is below the €3300 bar.