Why does it say here "Shiklei Zahav Mishkal Shesh Me'os", and in Shmuel II, 24:24 "b'Chesef Shekalim Chamishim"?
'Rashi', Rashi (Shmuel II, 24:24, citing Zevachim 116b, Sifri Devarim 62): David collected 50 Shekalim of silver from each Shevet, 600 in all, and gave to Aravnah for the value of [50 Shekalim of] gold. This was so all of Yisrael would have a share in the Mizbe'ach 1 .
Rashi (Zevachim 116b): He collected silver Shekalim from each Shevet worth 50 gold Shekalim. In all, he paid the value of 600 gold Shekalim.
Radak and Malbim, from Zevachim 116b: He collected silver Shekalim from each Shevet, equal to the weight of 50 gold Shekalim (gold Shekalim do not weigh the same as silver Shekalim. Tosfos (Kesuvos 99a DH Nasan) ? a gold Shekel weighs twice as much.)
Radak and Malbim (both citing Rebbi, Zevachim 116b): He paid 50 for the cattle, wood and place of the Mizbe'ach. 2 He paid 600 for the field, the place of the entire Beis ha'Mikdash. 3
Radak: This resolves "mi'Kol Shivteichem" with "b'Achad Shevatecha" (Devarim 12:5, 14). The Bayis was built in the portion of one tribe, but the money was from all the tribes.
Malbim: First, he bought only the place of the Mizbe'ach. After [he offered Korbanos, and] fire descended from Shamayim (verse 26), he knew that the place was chosen for the Beis ha'Mikdash, so he bought also the place around it.
Radak: The verses support this. There it mentions buying the cattle, wood and granary (where the Mizbe'ach would be) for 50. Here, it says he paid 600 for 'the place', i.e. of the entire Beis ha'Mikdash.
