Hmmm, you are kinda late, to start new shitty coin, should have made it in 2018
But even tho, answering your question how it works and what you need.
The price of coin, as of any other sellable product, depends on how much someone is willing to pay for it.
If you have a coin with 0 community, 0 plans, 0 ideas, then your coin will have no value.
To add value to a coin, you need a community. Bigger the community = more interested people to trade/mine = higher price. But it doesn't end here. Things aren't so simple.
To make people interested, you should promise something. The main goal of everyone in your community, is to make even more money. So your coin, should have ability to grow in price. It doesn't need to be a good coin, if you are a good marketer and you buy some promotions from influencers, then the price will jump without real reason, but it requires you to invest a lot.
Then, the most important moment, you need a place, where users will be able to sell/buy your coin anytime. No, your own site isn't good enough. You need to list your coin in a good crypto exchange. The best would be to list it in several exchanges. More exchanges = more ability to buy/sell = more stability = more traders selling and buying in different exchanges due to float price = more 24h trading volume = more interest.
Spoiler: Listing in any exchange is super expensive. Prices normally starts from 1 BTC. If the price is lower that 0.5BTC than the exchange is probably a scam.
(If you have huge community, then you can motivate them to donate for listing (crowdfunding). There were exchanges with listing donations. For example the min price to list is 0.5BTC, any user of your community can donate any amount, till the 0.5BTC)
Roadmap, important, but not really. It's only important for giving promises.
Concluding, the price of your coin, will depend on your community and infrastructure. If you list your coin on Binance and get 20k active users, then they will buy it for at least 1$.
If you have 500 people in your community and 0 infrastructure, selling your coin on your own site, then I wouldn't buy it for even 1 satoshi, cause I will not be able to sell it.
Basically that's it, you need to decide the price of your coin, based on infrastructure. Also you can create several offers, starting from 5 satoshi, till 200 or more. And see, what's the higher price that someone bought it and stick to that price.
