I went with the "non-donor" option. It IS slower, and it IS more expensive (although, surprisingly, it's still not that bad). One of my issues was that the "usual" donors (Miatas, for example) are extremely expensive around these parts (cheapest I found for a *seriously* wrecked Miata, when I was looking, was around $6K - the engine was probably dead anyway, as the front ancillaries were all crushed).
One of the advantages of the non-donor route is...you don't have to compromise. You're not "forced" into using parts that came on your donor (particularly those parts that are a long way from suitable, but you already have them, so...). This doesn't mean you have to buy new, off the shelf, expensive stuff - far from it. It just means you have to do more research, spook around wrecking yards & used parts places, etc., but you CAN find precisely the parts that will work the way you want, without compromising your design.
I realize this method is more complex, marginally more expensive, a little more time-consuming, and definitely not for everyone. BUT - don't discount it out of hand, either.
Every single time I work on my build, I thank my lucky stars that I chose the path I did. I have NEVER regretted going without a donor. My build is turning out to be exactly what I'd dreamed it would be, rather than a facsimile fraught with compromises I know I'd never be happy with.
All I'm saying is, consider the path carefully, figure out what your chosen use for the car will be, decide if you can live with compromise, and whichever path you choose...have fun!!
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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.
http://zetec7.webs.com/