In my neck of the woods, US Great Lakes, getting a nominal mounting, matting, glazing, and frame done WHOLESALE for THAT wide a print would cost well over $100. WHOLESALE.
Is the print matted? Glazed? It should be if this is serious.
Think of the time it took for that baby to run through your printer and all the materials and equipment it took to support it.
If I was on holiday, and saw a finished piece of that size that I liked, I would expect it to be priced around at least $300. More if the photographer was established. Much more if they were famous.
I'm not sure I agree with your low-ball pricing or the "bigger is better" philosophy. If you make any profit at all (I'm not seeing this) you will eventually be disenchanted with the adverse situation you created that is hard to undo.