pinaka labad na portion ana bro is ang training sa end user and maintenance sa system if ever ikaw pa mo shoulder ana...you might consider it sa imo package price...mostly customized system has a never ending feature mao na ka faet...if you sell it, you must see to it that the agreement binding u and the customer must be in favor sa imo nga side in terms of long term effect or else it causes you a lot of stress in the end... i have done before a payroll system for a company, luckily it was scrutinized by a CPA so the system abide most of the Philippine payroll system...honestly it was hard im not discouraging you but with that nTier system your aiming you might start consulting others especially those with accounting background....cheers!