Rick,
First and foremost, you must decide what your priority is. Authenticity? Performance? Cost? Fun factor? Take a look at all of the manufacturers and what they have to offer. You can find a links page on
www.gt40club.clara.net. Also search this sight for kit comparison.
Here's a brief rundown with plusses and minusses (I wont get into performance, as that is a skies-the-limit option)
ERA: made in the US, extremely authentic, monocoque, extremely expensive (at least $85K, waiting list
Roaring Forties: Australian made, but based on some US parts. Relatively authentic, spaceframe, uses easily sourced Audi trans, relatively expensive (probably $55K, now have a US dealer.
CAV: turnkey-minus only, now in monocoque, relatively authentic, relatively expensive ($65K?)
GT40 Replication: New Zealand made, spaceframe, relatively authentic, probably best bang-for-your-buck, but no instruction manual and you must source approximately 30% of the parts yourself. Uses Willwood brakes, which are easily sourced, but a Renault trans (scarce in US). Must ship from NZ and deal with customs. Has a good reputation, but rumor has it that the prices have just gone up (Alain, is this right? How much?)
KVA: UK made, first of the GT replicas, spaceframe, donor parts are UK based (not readily available in US), no manual, kits were extremely basic (body, frame, and some suspension). A second-hand KVA could be bought cheap, but you have to enjoy being a treasure hunter and plan on a multi-year build. Most have steering geometry issues. Fire up your welder and plasma cutter!
GTD, Sabre, Tornado: similar to KVA, but much more refined. Sold as complete or basic kits, most parts are readily available (but some only from UK), have manuals and some factory support, cost is in the middle, but suspension and brake mods seem to be recommended( additional $$$)
GT Supercars: still in prototype stage, but looks very authentic. US made, parts easily sourced, owner John Hester seems to put customer service high on his list of priorities. Cost should be in line with RF and CAV.
ASSP: Fiero rebody, probably least expensive, but looks like a caricature of a GT40, low performance
Scratch builts: Cheapest route on paper, but will ALWAYS cost more than anticipated. Cost and authenticity obviously vary, as do build times. This is the route I'm taking, hope to be painted and driving for around $30k
Complete cars: Best deal may be a completed GTD from the UK. Don't forget dealing with shipping and customs. Most of us on the forum want the pleasure of saying "I built it," but that sometimes costs more in the long run. And don't forget about all of those busted knuckles!
I know I left some out, and wasn't explicit in my descriptions, everyone please forgive me!!! It's just a rough guide to get you started. Good luck, Max.