Miata: springs, swaybars, Bilstein shocks, chassis bracing, Torsen LSD, larger aluminum wheels, and after 2001, upgraded brakes. A $900 option when new.
MINI: Springs, swaybars, shocks, $500.
I think the 4th generation Corvettes had some suspension options available. The Camaro had the 1LE package.
M030 was available from the 924 through the 968, and on the Boxster. I don't know about the 911 series. On the 944 S2, it included springs, swaybars, threaded-body front shocks, and upgraded brakes. LSD was a separate option.
I'm guessing that the Elise won't be as "dancable" as the 968...mid-engined cars have a different handling style than 50/50 front engine rear-drive cars. A good comparison would be the Miata and the MR2. The Miata lets you toy with the limits, recover quickly and be on your way. The MR2 requires more planning and commitment, but rewards you with quick responses and incredible grip under power. The 944/968 probably handle like great big Miatas. If my friend ever gets his S2 put back together, maybe I will find out first hand.
Did y'all catch the Grassroots Motorsports article in which a 944 ate up a comparably priced, comparable-vintage 911? All that, and a hatch for your stuff. Pretty cool.
As for resale value, a suspension option will probably be worth something if you are selling a car that's popular with racers or sportscar fans, and/or reasonably rare. On more common cars or cars that are sought for reasons other than performance, the suspension option will be overlooked by 95% of buyers and sellers, so it will never figure into the price.