having a very clean car will make is more easily to sell
as immobilisers go, i would go for anything less than a 5 point moby - can cost upto 1k, but its worth it esp if u dont have full comp insurance
buy a safc - there r bout $500 and bout 100 or so to get tuned - well worth it
then spend the rest of intake/zaust mods
maybe also a boost controller if u really want