"It is as good as cheap" does not really work well in English. How about "it is good as well as cheap," or "it is as good as it is cheap"? Both of these mean that the thing is good and it is also cheap
Dehbaash's suggestion, "it is just as good and cheaper too" is fine grammatically but the meaning is a bit different - it means that thing (A) is just as good as thing (B), but thing (A) also has the advantage of being cheaper than (B).