the parts prices are all on the web site. cams, springs, cam gears, cam belts, seals etc etc. New ECU's start at $2000
allow $800 labour to change cams including re-shimming. you would expect to see about 15kw improvement
allow $3000 labour to remove head, change cams, springs, re-shim, new stem seals, re-seat valves, fit new ECU, dyno tune etc. you would expect to see about 35kw improvement.
I expect to have a good high perforamce Gen 3 NA engine coming out of a car in the next few months. this might be a better deal for you as it already has all the good internals, forged pistons, lightened crank, ported head, cams, etc etc. Expect about $5000 for that engine