well...you need to buy at least 20 - 30 mb bandwidth, depend on your budget and how many client you have, in southeast asia a lot of small ISP which have average 10 to 50 MB, they bought from NAP around $700 - $1000/Mb/month, so you would need at least $3000/month. they could have 10 - 20 client which is small game center online and office, a lot of them grow up, have more bandwidth up to 100-200 mb with 50 - 100 client, i said about small ISP in asia
i doubt in europe/america such ISP exist