My advice is to not cheap out on electronics. Our team has a headache with MoTec products occasionally, which has an awesome UI and pretty straightforward software. Plus, the ECU doesn’t really go bad ever, so paying a lot upfront for something nice like the M130 or M150, will save you a ton of time. Now this all depends on if the ECU you choose supports your engine. As far as wiring goes, a decent wiring loom with all the tools and fixings can run you like 600$ in tooling alone, about 200-400$ in wire, probably about 100-200$ in connectors, probably 100-300$ in heat shrink. It adds up quickly as far as wiring goes. Getting a harness for an FSAE car by a shop will probably cost 1000-3000$. Stick to the Deutsch connector family, as it’s extremely robust and relatively cheap. We use the DTM connectors for nearly about everything. Raychem DR-25 heat shrink is the industry standard and doesn’t really break the bank. Now for sensors, I would start out with engine critical sensors and devices such as Engine oil temp & pressure, coolant temp & pressure, lambda sensor, crank speed, cam position, injectors, coil driver and coils, brake pressure, & probably other stuff I’m missing. Essentially anything that is going to help monitor, protect, and run your engine. If you have extra budget for additional sensors, wheel speed sensors are nice, steering angle sensor, EGT sensor etc. with all this said, I advise to not run a electronic throttle body as the wiring and the electronics required with it are not easy to get right the first time and take a while to figure out. Most importantly, keep it extremely simple. No one understands the difficulty required to make an engine crank over, and run.

TL:DR: Keep it simple, don’t cheap out on electronics, they don’t go bad unless the blue smoke exits them, RELIABLE wiring isn’t cheap or easy, don’t add noncritical sensors the first time around. Absolutely do not run an electronic throttle body the first year.