Sadly on the budget side of things I cant really compair as we have decided to spend the extra money to develop parts of the car, so its not standard by no means and wont be much like an exi when finished.(depends how hard you look).
When we placed the order a year ago, we were racing the the 750mc with a Honda B16 with twin 40 webers, after already collecting the kit, 2 days later Mark metioned that he was moving to the castle combe championship, so once we found out that the exi was going to be slow in class then we decided to change a load of things, biggest one was the engine from b16 to the k20, huge price difference but is well worth it if you can afford to. As we then went for more power, Mark @ Marlin was adiment that the driveshafts would not go straight with the engine still being foward, we poved him wrong.
, But over the year that we have been building the car within 3 months of saying yes we will order it, we had doubled our budget.
What ever you plan on spending add 5 Grand to it as new bits and piece come out and you then want the latest gadget to be fited to the car. Even though ours is a race car it is still going to be finished off as if it was going on the road, saving costs where we can but as we have spent so much already doing it the way we have, then we are going to stick with it untill this one is finsihed.
If we end up building a second car then it will be probably the most expensive exi built, with costings estimated at 35K but that is down to us (well me) wanting the best money can buy.
If i was any builder Honda K20 is the way to go, but build it to take a supercharger, (pm me if interested in any of our development work, i.e Honda runing gear & Body etc)
Jon