I have always loved Leon's work, and I know his product line and business practices were very well respected, but him going out of business is not the end of the world. There are still companies out there who sell similar products.
Model Car World, and Rainbow products still make laquer paints in factory colors for modelers.
If they dont have what you need, you can go to any paint jobber, and they can mix you small quantities of any factory paint code you want. Finding a shop that sells laquer may be hard, But Sherwin Williams and Dupont may have lapuer, depending on your location.
Also Urethanes happen to be really nice to work with, but will cost more. You do need to buy a hardener, but a $35 2 quart bottle will last for MANY bottles (but does have a shelf life, but I have used it for about a year after it was oppened). Any paint shop can mix any factory color you desire in this urethane, and they are used to doing small quantities for shops doing touch up work on 1:1 cars. Enough paint to do a few cars should run about $30. You can apply urethanes over lauqer primer if you want, but urethane primers are not too expensive. The best part of this type of paint, is that it cures very fast, as it is a catylised resin based paint. You can color sand it a day after its painted, and it will be like color sanding Laquer that you had to wait weeks to fully cure.
Again, its a shame to see Leon have to close his doors, but there are other alternatives out there.