Okay let's try this for determining the bond on a home. First of all look at my other post to determine the yearly bond payment. Now take number and divide by 12 to get what the monthly payment would be as you will need this for a reverse loan amortization calculation below.
Go to this site,
http://www.sharewareisland.com/mortgagecalculator.aspx (if the link does not work cut and paste it into your browser) and first click on the reverse button under the all clear. You will now have to enter the necessary information. You know the payments are for 30 years, you know the payment (from the number you arrived at above) and the one number that is iffy is the interest. At present I believe the interest is at 7%.
Okay here is an example. Over in Pennecamp there are some beautiful premier homes on Lake Ridge Dr that I was told the bond is about $48,000. Looking at the records for that street I see that the bond payment is $3,914.12 per year or $326.18 per month. The total over 30 is $117,423.60. Now entering that information into the reverse loan amortization calculator I come up with a bond of $49,027.32. About a grand off from the rough number now being kicked around for premier homes in that area.
A word of caution and this may not work in all cases. If you are trying to do the same calculation on say a home north of 466 you will have to know the interest rate and term of the bond. I understand these have changed over the years.