From your description, you may not have an "original 1984" Mac.
Please post the model number (on a sticker on the back,) and the first seven characters of the serial number (either on the back, bottom, or under the "lip" up front.)
The original 1984 Mac used 400 KB floppies, not 800 KB. No Macintosh could take 4 MB (I assume you meant MB, not KB,) until the 1986 Macintosh Plus. The Plus was *VERY* common, even a pristine one is worth maybe $20 now.
You likely have either a Macintosh Plus, or an earlier model that has been upgraded to Plus-status (which was a common upgrade.) In either case, it's not worth a lot.
Even if it was a perfect-condition, truly stock 1984-released Macintosh 128, with all original packaging, it would be worth - at most - $500. As
If it doesn't have its packaging, you're looking at $100-$200.
As for having unopened ones? It has been known to happen. A school or a business will buy a lot of systems, including some as spares that sit unopened. Someone posted a year or two ago about finding (and opening,) a factory-sealed PCjr that was exactly that, school old stock.