I have been travelling all around America and think the time is right to visit my home country Latvia. I came to the USA with my parents when I was just 1 year old and now have a US green card. I think it's time to visit Latvia and talked to a cousin of mine back in Latvia about getting a Latvian passport and he talked rather of getting it online via stampedpapers at on their page entittled " Order passports online". How true can this be and what is the best procedure for a person in my situation?
This is way outside my expertise, so I have no real advice to give you. However, it seems to me the best way to move forward is to contact the Lavtian Embassay or consulate here in the US. The embassy is in Washington DC, I don't know how many consulates there are (you can Google it) but there is at least one in New York. Give the consulate (or embassy) closest to you a call and ask for direction on how to get a passport.
This is not what you asked, and is frankly none of my business, but if you have been here since you were 1 year old and have a green card, you may want to seriously consider getting US citizenship. I don't know the specifics of your situation, but it may be the best way to go.
There are a lot of services online that charge a markup merely to serve as a conduit to what someone could do directly with the government. It's not quite a "scam," because they're doing what they said they were going to, but you pay them $400 for something you could do on your own for $200, and they don't provide any value in the process.
It's common to come across such websites when looking for visa processing.
This website appears to be one such service.