It also stresses that the libreta is not the only means of acquiring goods available to a Cuban citizen, as these and other products are freely available on the mercado libre and mercado paralelo, and of course in the numerous supermarkets and stores that sell goods in convertible pesos or euros. The prices in the ration book are about 20 times lower than the free market.
The passage explains that while the libreta is a method of obtaining goods, it's not the only way. Other options like the free market and parallel market, along with supermarkets selling goods in convertible pesos or euros, offer alternative avenues for acquiring goods. The prices for rationed items are significantly lower than those found on the free market.