A % tax on the cost of the property would be pretty simple. Can't buy without paying the tax up front. It's usually the more complicated taxes that have exceptions to rules that are exploitable. It's hard to find exploits in simple rules.
Btw, I would _not_ charge a transaction tax. Charge them every year for holding the property. (Eg charge whoever holds the property on New Year, the market will do the rest.)
That way you don't impede transactions.
Just use the tax take to finance local goods and service and to lower other local taxes.