No sería mas fácil que lo hicieras así:
Cita: Private Sub ddlModels_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlModels.SelectedIndexChanged
txtPrice.Text = ddlModels.SelectedItem.Value.ToString("##,##")
txtPrice.ReadOnly = True
txtcuotas.Text = String.Empty
End Sub
Salu2