To hold otherwise would be to encourage estimates of fair market value of such rights on the basis of pure speculation and surmise. Weigl v. Commissioner, 84 T.C. at 1216; Frank v. Commissioner, 54 T.C. 75, 94 (1970), affd. 447 F.2d 552 (7th Cir. 1971). That policy is not altered by the enactment of section 83.