As Ranger sez: Burn that list!
Never add up what you spend. If you have to ask, you can’t afford it. You will spend WAYYYYY more than you will ever admit. No buddy builds a competitive car for 10k. Even if you do it all yourself. You will spend at least 20. Anybody who tells you different is delusional. Plus if you run the whole season, you will spend close to 1k per weekend, if nothing goes wrong. The only guys who will be honest about costs are the guys who have quit. There is a reason they quit, may be they’ll tell you. If the field is deep, you will spend 50% to 100% more to get up front. Guys who have shops are still spending that much, they just don’t add up their time.
Yes Spec E30 is about the cheapest group you can join to do actual racing, but if it is a big group you will spend a lot more to get and stay up front.
It is like remodeling your house, it always cost more. There are a few rare people who can keep their cost at a specific budget. May be you are one of those rare people. Otherwise just remember this is called RACING. Think Horses. Think Boats. Think KIDS. Think Wives. They all cost us more than we expect or will admit.
Have Fun. Keep it Real. Never discuss costs. Just keep building and eventually you will be out there and learning and getting faster and eventually you will decide how much you choose to spend and where you are happy on the grid.
Best and cheapest approach is buy a complete car from someone who is actually racing but is quitting. Devinneys car was an absolute steal, don’t know if his car is available, but truly that is the cheapest way to do it!