An opinion
The driving consideration is the price you are willing to pay. If you seek a spider in the 5k or less range, then there you go. I'm no expert, but my sense of the market is that pretty nice S3-S4 spiders are available right now in the 7,500-10k range. There are potential bargains, with good investment potential, in that 7500-10K range. For 10k+, you have an opportunity to purchase an exceptional spider, if you must, if you buy wisely. As for which year, that is a personal decision, but from what I can tell, there are a fair quantity of very late 80s S3s and 90's S4 spiders available, in very good original condition. It may take a few months to find the right one, but this should not be a rushed purchase. My subjective preference is the all Black S4. In that iteration, the spider has the best electronics, solid mechanicals, as well as a body that pays homage to the original S1. It appears both fresh and vintage. I am constantly asked what year it is and I think people expect me to say "1968". The all Black interior, exterior and top finish unifies all the modern bits and pieces, all the little things that otherwise violate the eye. Just one person's subjective opinion.
