My friend, when people sell a business in the US, they generally ask for between 6 months and 1.5 years of what the profit is from the business. This can vary because the business could include customer lists, equipment, buildings, land, and other things that have value.
With web sites, you have what the site is generating in income, but also the value of the site design, the value of the domain, the actual traffic numbers, mailing lists, and other things that may have value.
So if you are looking to buy a web site that is generating $100 a month profit, you should expect to pay at least $400 - $1,600. What I see in the US is that a lot of sellers have built a site, spent many, many hours and/or much money to have a site that is making money, but then they think they will get back all of that effort and time and ask $3,000 for a site that earns $50 a month! Sometimes they can sell them, but generally those that have experience consider it a bad business investment.
A site's potential is also something to consider, but that is a hard thing to place a value on in most cases and is very subjective.
So if I have a site that is earning $125 a month, you can get an idea of about how much I am going to ask for it. Yes, it is a considerable investment, AND you have to be careful about what you buy.
I am curious why you want to by a site that does not need marketing and promotion, but you offer to provide personalized services? Would it not make sense to buy one or more good sites with potential and do some work to make then generate income for you? I consider it like buying a small house you can afford, fixing it up and finding a renter. You keep fixing it up and making it nicer and charge more rent. Then someday you sell it and if you are lucky, get paid for your hard work.
