about $800.00 and your blaster will be faster !!! lol
between your bigbore kit, port job, weisco piston and a good high volume pipe, after that youll also prolly need a bigger carb and might as well throw in some good reeds while your at it. , id would save up a $1000 and do everything right. or look for used stuff, but me personaly, i dont like to do used. to build an engine RIGHT isnt cheap. dont forget the small stuff that adds up quick like a gasket kit, while your engien is apart you might as well throw in new bearings, theres another 50 to 100..adds up real quick, im building another yz250 as we speak and man the dollars sure do add up if ya do it right.