Finding postcodes near a known postcode

I am building a website where I need to find people based on their postcode and have been searching the past month for a good and cheap solution. From solutions costing around €2000 down to solutions costing €500 down to one which costs only €99 for a latitude/longitude database of Dutch postcodes, to be found at GEODATAS.net. On their website is sample code present and I converted the PHP-version to Lasso 8 code. —> Click here for how-to and demo code.