MasterKamera
Your comment 'with Humbrol enamels gone now" confuses me. I don't know where you are based but Humbrol enamels are among the easiest to find either via hobby shops or through mail order options.
Your concerns about finding a paint line are, with respect, over-thinking the problem. Its not that difficult.
Unfortunately these days as people use Forum names only with no indication of where you are based, it makes it difficult for us to help steer you to an affordable paint source. On that basis I suggest you check out local toy or hobby/ craft stores for paints, and then online mail order in your country or Ebay or similar in your country.
If, for example you live in Australia and buy paint mail order from America, you will pay a fortune in postage. Buy local wherever possible for the cheapest option. Many hobby shops do a 'free postage for sales over $XX value". I often buy paint in bulk like this and get free postage. Buy one tin of paint from America and it costs more in postage than the kit you are going to paint it on.
As for which paint to get, buy an assortment of primary colours, e.g. black, white, yellow, red etc. Then check each model's instructions booklet- almost all recommend specific paint brands and colours for their kits. Build up a stock of these colours and over time you will assemble a 'library' of all the key paints you will need.
Also a good brush finish depends on good paint and good brushes. Buy some quality brushes from hobby or art/ craft shops. They will give you years of service and ensure a smooth, blemish free surface.
As for colour charts, they are very subjective and can vary depending on who compiled them. Google can help.
So, short version- look at the instructions of the kit you want to make then find the colours they recommend. Buy from as local a source as possible to keep postage costs down.
As said earlier, some brands are easier to find/ use than others. Find the paint brand that you like/ can afford and are happy to use then build up your stocks of paint. Over time you will have a good stock of paint to cover future builds.
Dave Wilson
Gold Coast
Australia