There really isnt any top model when it comes to the 1998 240SX(SE i suppose is the top). The S15 conversion to the headlights includes: headlights, core support, fenders (some metal some FB) hood, bumper and sometimes HID. Look for the rough general price to be about $3000-$3500 for the body and headlight pieces, $500 for HID and probably little less than $1000 for paint.
*Do note that an aftermarket JDM bumper kit, CF hood or sidemarkers will make the general prices increase.
This has been the topic of many discussions on this board so next time search.
Heres some places to get conversions
http://www.autoimaging.com/sho...137cf or http://www.afterdark-tuning.co....html