not to mention you don't just fund in stealth
you could not take an aeroplane that was not designed to be low observable\stealth and just throw money at it and make it stealth\low observable without a redesign of the whole skin and other elements, stealth and low observability are design doctrines that have to be integrated from the very beginning, it's not "we'l design the plane then you put the stealth on it later"
there is a reason the f-117 looks so unusual and has such unstable flight characteristics, there is also a reason it has such an incredibly small radar profile <well, several really> there is a reason the f-16 has such a large radar signature and flys in the manner it does, design doctrine
and I know RADAR, I'm just to lazy to caps it every time, same as LASER, which no one bothers to cap out anymore....